Fishkeeping - AbsoluteAstronomy.com

Fishkeeping is a popular hobby

Hobby

A hobby is a regular activity or interest that is undertaken for pleasure, typically done during one's leisure time.- Etymology :A hobby horse is a wooden or wickerwork toy made to be ridden just like a real horse...

concerned with keeping fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

in a home aquarium

Aquarium

An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...

or garden pond

Pond

A pond is a body of standing water, either natural or man-made, that is usually smaller than a lake. A wide variety of man-made bodies of water are classified as ponds, including water gardens, water features and koi ponds; all designed for aesthetic ornamentation as landscape or architectural...

. There is also a fishkeeping industry, as a branch of agriculture

Agriculture

Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

Types of fishkeeping systems

Fishkeepers are often known as "aquarists", since many of them are not solely interested in keeping fish. The hobby can be broadly divided into three specific disciplines according to the type of water the fish tolerate: freshwater

Freshwater

Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

, brackish

Brackish water

Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...

, and marine

Marine (ocean)

Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

(also called saltwater) fishkeeping.

Freshwater

Freshwater fishkeeping
Freshwater aquarium
A freshwater aquarium is a receptacle that holds one or more freshwater aquatic organisms for decorative, pet-keeping, or research purposes. Modern aquariums are most often made from transparent glass or acrylic glass. Typical inhabitants include fish, plants, amphibians, and invertebrates, such as...

is by far the most popular branch of the hobby, with even small pet stores often selling a variety of freshwater fish, such as goldfish

Goldfish

The goldfish is a freshwater fish in the family Cyprinidae of order Cypriniformes. It was one of the earliest fish to be domesticated, and is one of the most commonly kept aquarium fish....

, guppies

Guppy

The guppy , also known as the millionfish, is one of the most popular freshwater aquarium fish species in the world. It is a small member of the Poeciliidae family [females long, males long] and like all other members of the family, is live-bearing....

, and angelfish

Pterophyllum

Pterophyllum is a small genus of freshwater fish from the family Cichlidae known to most aquarists as "Angelfish". All Pterophyllum species originate from the Amazon River, Orinoco River and Essequibo River basins in tropical South America...

. While most freshwater aquaria are community tanks containing a variety of compatible species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

, single-species breeding aquaria are also popular. Livebearing

Live-bearing aquarium fish

Live-bearing aquarium fish, often simply called livebearers, are fish that retain the eggs inside the body and give birth to live, free-swimming young.-Common aquarium livebearers:...

fish such as mollies and guppies are among those most easily raised in captivity, but aquarists also regularly breed many types of cichlid

Cichlid

Cichlids are fishes from the family Cichlidae in the order Perciformes. Cichlids are members of a group known as the Labroidei along with the wrasses , damselfish , and surfperches . This family is both large and diverse. At least 1,300 species have been scientifically described, making it one of...

, catfish

Catfish

Catfishes are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...

, characin

Characidae

The Characidae, characids or characins are a family of freshwater subtropical and tropical fish, belonging to the order Characiformes. The name "characins" is the historical one, but scientists today tend to prefer "characids" to reflect their status as a by and large monophyletic group at family...

, and killifish

Killifish

A killifish is any of various oviparous cyprinodontiform fish . Altogether, there are some 1270 different species of killifish, the biggest family being Rivulidae, containing more than 320 species...

.

Many fishkeepers create freshwater aquascapes where the focus is on aquatic plant

Aquatic plant

Aquatic plants are plants that have adapted to living in aquatic environments. They are also referred to as hydrophytes or aquatic macrophytes. These plants require special adaptations for living submerged in water, or at the water's surface. Aquatic plants can only grow in water or in soil that is...

s as well as fish. These aquaria include "Dutch Aquaria", named for European aquarists who designed them. In recent years, one of the most active advocates of the heavily planted aquarium is the Japanese aquarist Takashi Amano

Takashi Amano

is a photographer, designer and Aquarist.His interest in aquaria led him to create the Japanese company Aqua Design Amano.Takashi Amano is one of the most influential people in the freshwater aquascaping community. He can largely be credited with introducing Japanese gardening concepts such as...

.

Garden ponds

Water garden

Water gardens, also known as aquatic gardens, are a type of man-made water feature. A water garden is defined as any interior or exterior landscape or architectural element whose primarily purpose is to house, display, or propagate a particular species or variety of aquatic plant...

are in some ways similar to freshwater aquaria, but are usually much larger and exposed to ambient weather. In the tropics, tropical fish can be kept in garden ponds, but in the temperate zone species such as goldfish, koi

Koi

or more specifically , are ornamental varieties of domesticated common carp that are kept for decorative purposes in outdoor koi ponds or water gardens....

, and orfe work better.

Saltwater

Marine aquaria
Marine aquarium
A marine aquarium is an aquarium that keeps marine plants and animals in a contained environment. Marine aquaria are further subdivided by hobbyists into fish only , fish only with live rock , and reef aquaria. Fish only tanks often showcase large or aggressive marine fish species and generally...

are generally more difficult to maintain and the livestock is significantly more expensive. As a result this branch tends to attract more experienced fishkeepers. Marine aquaria can be exceedingly beautiful, due to the attractive colors and shapes of the coral

Coral

Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...

s and the coral reef

Coral reef

Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...

fish they host. Temperate zone marine fish are not as commonly kept in home aquaria, primarily because they do not thrive at room temperature. Coldwater aquaria must provide cooler temperature via a cool room (such as an unheated basement) or a refrigeration

Refrigeration

Refrigeration is a process in which work is done to move heat from one location to another. This work is traditionally done by mechanical work, but can also be done by magnetism, laser or other means...

device known as a 'chiller'.

Marine aquarists often attempt to recreate a coral reef in their aquaria using large quantities of living rock

Live rock

Live rock is rock from the ocean that has been introduced into a saltwater aquarium. Along with live sand, it confers to the closed marine system multiple benefits desired by the saltwater aquarium hobbyist...

, porous calcareous rocks

Aragonite

Aragonite is a carbonate mineral, one of the two common, naturally occurring, crystal forms of calcium carbonate, CaCO3...

encrusted with coralline algae

Coralline algae

Coralline algae are red algae in the order Corallinales. They are characterized by a thallus that is hard because of calcareous deposits contained within the cell walls...

, sponges, worm

Worm

The term worm refers to an obsolete taxon used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals, and stems from the Old English word wyrm. Currently it is used to describe many different distantly-related animals that typically have a long cylindrical...

s, and other small marine organisms. Larger corals as well as shrimp

Shrimp

Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...

s, crab

Crab

True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...

s, echinoderm

Echinoderm

Echinoderms are a phylum of marine animals. Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone....

s, and mollusks are added later on, once the aquarium has matured, as well as a variety of small fish. Such aquaria are sometimes called reef tanks

Reef aquarium

A reef aquarium or reef tank is an marine aquarium that prominently displays live corals and other marine invertebrates as well as fish that play a role in maintaining the coral reef environment...

Brackish water

Brackish water aquaria
Brackish-water aquarium
A brackish water aquarium is an aquarium where the water is brackish . The range of "saltiness" varies greatly, from near freshwater to near marine and is often referred to as specific gravity or salinity. Brackish water aquaria is a popular specialization within the fishkeeping hobby...

combine elements of the other types, with salinity

Salinity

Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...

that must stay between that of freshwater and seawater. Brackish water fish come from habitats with varying salinity, such as mangrove

Mangrove

Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...

s and estuaries

Estuary

An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....

, and do not thrive if kept permanently in freshwater. Although brackish water aquaria are not necessarily familiar to inexperienced aquarists, many species prefer brackish water, including some mollies, many gobies

Goby

The gobies form the family Gobiidae, which is one of the largest families of fish, with more than 2,000 species in more than 200 genera. Most are relatively small, typically less than 10 cm in length...

, some pufferfish, monos

Monodactylidae

The Monodactylidae is a family of fish within the Perciformes commonly referred to as monos, moonyfishes or fingerfishes. All are strongly laterally compressed with an approximately disc-shaped body and tall anal and dorsal fins. Unusually for fish, there are scales on the dorsal fin and sometimes...

, scats

Scatophagidae

The scats are a small family, Scatophagidae, of fishes in the order Perciformes.They are small fish native to the Indian and western Pacific Ocean that have been popular in the aquarium trade in the last 30 years...

, and virtually all the freshwater soles

Soleidae

The true soles are a family, Soleidae, of flatfishes, and include species that live in salt water and fresh water. They are bottom-dwelling fishes feeding on small crustaceans and other invertebrates. Other flatfishes are also known as soles....

The origins of fishkeeping

Fish have been raised as food in pools and ponds for thousands of years. Brightly colored or tame specimens of fish in these pools have sometimes been valued as pets rather than food. Many other cultures kept fish for both functional and decorative purposes.

Ancient Sumer

Sumer

Sumer was a civilization and historical region in southern Mesopotamia, modern Iraq during the Chalcolithic and Early Bronze Age....

ians kept wild-caught fish in pond

Pond

s, before preparing them for meals. Depictions of the sacred fish of Oxyrhynchus

Oxyrhynchus

Oxyrhynchus is a city in Upper Egypt, located about 160 km south-southwest of Cairo, in the governorate of Al Minya. It is also an archaeological site, considered one of the most important ever discovered...

kept in captivity in rectangular temple pools have been found in ancient Egyptian art.

Similarly, Asia has experienced a long history of stocking rice paddies

Paddy field

A paddy field is a flooded parcel of arable land used for growing rice and other semiaquatic crops. Paddy fields are a typical feature of rice farming in east, south and southeast Asia. Paddies can be built into steep hillsides as terraces and adjacent to depressed or steeply sloped features such...

with freshwater fish suitable for eating, including various types of catfish

Catfish

and cyprinid

Cyprinid

The family Cyprinidae, from the Ancient Greek kyprînos , consists of the carps, the true minnows, and their relatives . Commonly called the carp family or the minnow family, its members are also known as cyprinids...

. Selective breeding

Selective breeding

Selective breeding is the process of breeding plants and animals for particular genetic traits. Typically, strains that are selectively bred are domesticated, and the breeding is sometimes done by a professional breeder. Bred animals are known as breeds, while bred plants are known as varieties,...

of carp

Carp

Carp are various species of oily freshwater fish of the family Cyprinidae, a very large group of fish native to Europe and Asia. The cypriniformes are traditionally grouped with the Characiformes, Siluriformes and Gymnotiformes to create the superorder Ostariophysi, since these groups have certain...

into today's popular and completely domesticated koi

Koi

or more specifically , are ornamental varieties of domesticated common carp that are kept for decorative purposes in outdoor koi ponds or water gardens....

and goldfish

Goldfish

The goldfish is a freshwater fish in the family Cyprinidae of order Cypriniformes. It was one of the earliest fish to be domesticated, and is one of the most commonly kept aquarium fish....

began over 2,000 years ago in Japan and China, respectively. The Chinese brought goldfish indoors during the Song Dynasty

Song Dynasty

The Song Dynasty was a ruling dynasty in China between 960 and 1279; it succeeded the Five Dynasties and Ten Kingdoms Period, and was followed by the Yuan Dynasty. It was the first government in world history to issue banknotes or paper money, and the first Chinese government to establish a...

to enjoy them in large ceramic vessels.

In Medieval Europe, carp

Carp

pools were a standard feature of estates and monasteries, providing an alternative to meat on feast days

Calendar of saints

The calendar of saints is a traditional Christian method of organizing a liturgical year by associating each day with one or more saints and referring to the feast day of said saint...

when meat could not be eaten for religious reasons.

Marine fish have been similarly valued for centuries. Wealthy Romans kept lamprey

Lamprey

Lampreys are a family of jawless fish, whose adults are characterized by a toothed, funnel-like sucking mouth. Translated from an admixture of Latin and Greek, lamprey means stone lickers...

s and other fish in salt water pools. Tertullian

Tertullian

Quintus Septimius Florens Tertullianus, anglicised as Tertullian , was a prolific early Christian author from Carthage in the Roman province of Africa. He is the first Christian author to produce an extensive corpus of Latin Christian literature. He also was a notable early Christian apologist and...

reports that Asinius Celer paid 8000 sesterces

Sestertius

The sestertius, or sesterce, was an ancient Roman coin. During the Roman Republic it was a small, silver coin issued only on rare occasions...

for a particularly fine mullet

Mullet (fish)

The mullets or grey mullets are a family and order of ray-finned fish found worldwide in coastal temperate and tropical waters, and in some species in fresh water. Mullets have served as an important source of food in Mediterranean Europe since Roman times...

. Cicero

Cicero

Marcus Tullius Cicero , was a Roman philosopher, statesman, lawyer, political theorist, and Roman constitutionalist. He came from a wealthy municipal family of the equestrian order, and is widely considered one of Rome's greatest orators and prose stylists.He introduced the Romans to the chief...

reports that the advocate

Advocate

An advocate is a term for a professional lawyer used in several different legal systems. These include Scotland, South Africa, India, Scandinavian jurisdictions, Israel, and the British Crown dependencies of Jersey, Guernsey and the Isle of Man...

Quintus Hortensius

Quintus Hortensius Hortalus was a Roman orator and advocate.At the age of nineteen he made his first speech at the bar, and shortly afterwards successfully defended Nicomedes IV of Bithynia, one of Rome's dependants in the East, who had been deprived of his throne by his brother. From that time...

wept when a favored specimen died. Rather cynically, he referred to these ancient fishkeepers as the Piscinarii, the "fish-pond owners" or "fish breeders", for example when saying that ...the rich (I mean your friends the fish-breeders) did not disguise their jealousy of me.

Aquarium maintenance

Ideal aquarium ecology

Ecology

Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...

reproduces the balance found in nature in the closed system

Isolated system

In the natural sciences an isolated system, as contrasted with an open system, is a physical system without any external exchange. If it has any surroundings, it does not interact with them. It obeys in particular the first of the conservation laws: its total energy - mass stays constant...

of an aquarium. In practice it is virtually impossible to maintain a perfect balance. As an example, a balanced predator-prey relationship

Predation

In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...

is nearly impossible to maintain in even the largest aquaria. Typically, an aquarium keeper must actively maintain balance in the small ecosystem

Ecosystem

An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....

s that aquaria provide.

Balance is facilitated by larger volumes of water which dilute the effects of a systemic shock

Systemic shock

A systemic shock is a shock to any system that perturbs a system enough to drive it out of equilibrium. Systemic shocks occur in a wide range of fields, ranging from medicine to economics to engineering...

. For example, the death of the only fish in a 10 litres (21.1 US pt) tank causes dramatic changes in the system, while the death of that same fish in a 400 litres (845.4 US pt) tank that holds many fish creates only a minor imbalance. For this reason, hobbyists often favor larger tanks when possible, as they require less intensive attention.

A variety of nutrient cycles

Biogeochemical cycle

In ecology and Earth science, a biogeochemical cycle or substance turnover or cycling of substances is a pathway by which a chemical element or molecule moves through both biotic and abiotic compartments of Earth. A cycle is a series of change which comes back to the starting point and which can...

are important in the aquarium. Dissolved oxygen enters at the surface water-air interface or through the actions of an air pump

Pump

A pump is a device used to move fluids, such as liquids, gases or slurries.A pump displaces a volume by physical or mechanical action. Pumps fall into three major groups: direct lift, displacement, and gravity pumps...

. Carbon dioxide

Carbon dioxide

Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

escapes into the air. The phosphate

Phosphate

A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...

cycle is an important, although often overlooked, nutrient cycle. Sulfur

Sulfur

Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

, iron

Iron

Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

, and micronutrient

Micronutrient

Micronutrients are nutrients required by humans and other living things throughout life in small quantities to orchestrate a whole range of physiological functions, but which the organism itself cannot produce. For people, they include dietary trace minerals in amounts generally less than 100...

s enter the system as food and exit as waste. Appropriate handling of the nitrogen cycle

Nitrogen cycle

The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms. This transformation can be carried out by both biological and non-biological processes. Important processes in the nitrogen cycle include fixation, mineralization, nitrification, and denitrification...

, along with a balanced food supply and consideration of biological loading, is usually enough to keep these nutrient cycles in adequate equilibrium.

Water conditions

The solute

Solution

In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...

content of water is perhaps the most important aspect of water conditions, as total dissolved solids

Total dissolved solids

Total Dissolved Solids is a measure of the combined content of all inorganic and organic substances contained in a liquid in: molecular, ionized or micro-granular suspended form. Generally the operational definition is that the solids must be small enough to survive filtration through a sieve...

and other constituents can dramatically impact basic water chemistry, and therefore how organisms interact with their environment. Salt content, or salinity

Salinity

, is the most basic classification of water conditions. An aquarium may have freshwater

Freshwater

(salinity below 0.5 PPT), simulating a lake or river environment; brackish water

Brackish water

(a salt level of 0.5 to 30 PPT), simulating environments lying between fresh and salt, such as estuaries

Estuary

An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....

; and salt water or seawater

Seawater

Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...

(a salt level of 30 to 40 PPT), simulating an ocean or sea environment. Even higher salt concentrations are maintained in specialized tanks for raising brine organisms.

Several other water characteristics result from dissolved materials in the water, and are important to the proper simulation of natural environments. Saltwater is typically alkaline, while the pH

In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

of fresh water varies. "Hardness" measures overall dissolved mineral content; hard or soft water

Hard water

Hard water is water that has high mineral content . Hard water has high concentrations of Ca2+ and Mg2+ ions. Hard water is generally not harmful to one's health but can pose serious problems in industrial settings, where water hardness is monitored to avoid costly breakdowns in boilers, cooling...

may be preferred. Hard water is usually alkaline, while soft water is usually neutral to acidic. Dissolved organic content

Chemical oxygen demand

In environmental chemistry, the chemical oxygen demand test is commonly used to indirectly measure the amount of organic compounds in water. Most applications of COD determine the amount of organic pollutants found in surface water or wastewater, making COD a useful measure of water quality...

and dissolved gases content are also important factors.

Home aquarists typically use modified tap water supplied through their local water supply network

Water supply network

A water supply system or water supply network is a system of engineered hydrologic and hydraulic components which provide water supply. A water supply system typically includes:# A drainage basin ;...

. Because of the chlorine

Chlorine

Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

used to disinfect drinking water supplies for human consumption, tap water cannot be immediately used. In the past, it was possible to "condition" the water by simply letting the water stand for a day or two, which allows the chlorine

Chlorine

to dissipate. However, chloramine

Chloramine

Chloramines are derivatives of ammonia by substitution of one, two or three hydrogen atoms with chlorine atoms. Monochloramine is an inorganic compound with the formula NH2Cl. It is an unstable colourless liquid at its melting point of -66° temperature, but it is usually handled as a dilute...

became popular in water treatment

Water treatment

Water treatment describes those processes used to make water more acceptable for a desired end-use. These can include use as drinking water, industrial processes, medical and many other uses. The goal of all water treatment process is to remove existing contaminants in the water, or reduce the...

because it stays longer in the water. Additives are available to remove chlorine or chloramine and suffice to make the water ready. Brackish or saltwater aquaria require the addition of a mixture of salts and other minerals.

More sophisticated aquarists may modify the water's alkalinity, hardness, or dissolved content of organics and gases. This can be accomplished by additives such as sodium bicarbonate

Sodium bicarbonate

Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula Na HCO3. Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder. It has a slightly salty, alkaline taste resembling that of washing soda . The natural mineral form is...

to raise pH. Some aquarists filter or purify their water using one of two processes: deionization

Purified water

Purified water is water from any source that is physically processed to remove impurities. Distilled water and deionized water have been the most common forms of purified water, but water can also be purified by other processes including reverse osmosis, carbon filtration, microfiltration,...

or reverse osmosis

Reverse osmosis

Reverse osmosis is a membrane technical filtration method that removes many types of large molecules and ions from solutions by applying pressure to the solution when it is on one side of a selective membrane. The result is that the solute is retained on the pressurized side of the membrane and...

. In contrast, public aquaria with large water needs often locate themselves near a natural water source (such as a river, lake, or ocean) in order to have easy access to water that requires only minimal treatment.

Water temperature

Temperature

Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...

forms the basis of one of the two most basic aquarium classifications: tropical

Tropics

The tropics is a region of the Earth surrounding the Equator. It is limited in latitude by the Tropic of Cancer in the northern hemisphere at approximately N and the Tropic of Capricorn in the southern hemisphere at S; these latitudes correspond to the axial tilt of the Earth...

vs. cold water

Coldwater fish

Coldwater fish, in the context of aquariums, refers to fish species that prefer cooler water temperatures than tropical fish, typically below . Some examples are koi and goldfish...

. Most fish and plant species tolerate only a limited range of water temperatures: Tropical or warm water aquaria maintain an average temperature of about 25 °C (77 °F) are much more common, and tropical fish

Tropical fish

Tropical fish include fish found in tropical environments around the world, including both freshwater and salt water species.Tropical fish are popular as aquarium fish, due to their often bright coloration...

are among the most popular aquarium denizens. Cold water aquaria maintain temperatures below the room temperature. More importantly than the range is temperature consistency; most organisms are not accustomed to sudden changes in temperatures, which can cause shock and lead to disease. Water temperature can be regulated with a combined thermometer

Thermometer

Developed during the 16th and 17th centuries, a thermometer is a device that measures temperature or temperature gradient using a variety of different principles. A thermometer has two important elements: the temperature sensor Developed during the 16th and 17th centuries, a thermometer (from the...

and heating or cooling unit.

Water movement can also be important in accurately simulating a natural ecosystem. Fish may prefer anything from still water up to swift, simulated currents

Current (fluid)

A current in a fluid is the magnitude and direction of flow within that fluid. An air current presents the same properties for a gaseous medium.Kinds of fluid currents include.* Boundary current* Current , a current in a river or stream...

. Water movement can be controlled through the use of aeration from air pumps, powerheads

Powerhead (pump)

An aquarium powerhead is a water pump completely submerged into an aquarium to circulate water throughout it. some can be just plopped in, put in the back so the water in the front will go one way to simulate a river for trout, or used as a fountain. The term "powerhead" is actually a brand name....

, and careful design of water flow (such as location of filtration system points of inflow and outflow).

Nitrogen cycle

Fish are animals and generate waste as they metabolize food, which aquarists must manage. Fish, invertebrates, fungi

Fungus

A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...

, and some bacteria excrete nitrogen

Nitrogen

Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

in the form of ammonia

Ammonia

Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

(which converts to ammonium

Ammonium

The ammonium cation is a positively charged polyatomic cation with the chemical formula NH. It is formed by the protonation of ammonia...

in acidic water) and must then pass through the nitrogen cycle

Nitrogen cycle

. Ammonia is also produced through the decomposition

Decomposition

Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...

of plant and animal matter, including fecal

Feces

Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...

matter and other detritus

Detritus

Detritus is a biological term used to describe dead or waste organic material.Detritus may also refer to:* Detritus , a geological term used to describe the particles of rock produced by weathering...

. Nitrogen waste products become toxic to fish and other aquarium inhabitants above a certain concentration.

The process

A well-balanced tank contains organisms that metabolize

Metabolism

Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...

the waste products of other inhabitants. Nitrogen waste is metabolized in aquaria by a type of bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

known as nitrifiers

Nitrification

Nitrification is the biological oxidation of ammonia with oxygen into nitrite followed by the oxidation of these nitrites into nitrates. Degradation of ammonia to nitrite is usually the rate limiting step of nitrification. Nitrification is an important step in the nitrogen cycle in soil...

(genus Nitrosomonas
Nitrosomonas
Nitrosomonas is a genus comprising rod shaped chemoautotrophic bacteria.This rare bacteria oxidizes ammonia into nitrite as a metabolic process. Nitrosomonas are useful in treatment of industrial and sewage waste and in the process of bioremediation. They are important in the nitrogen cycle by...

). Nitrifying bacteria metabolize ammonia into nitrite

Nitrite

The nitrite ion has the chemical formula NO2−. The anion is symmetric with equal N-O bond lengths and a O-N-O bond angle of ca. 120°. On protonation the unstable weak acid nitrous acid is produced. Nitrite can be oxidised or reduced, with product somewhat dependent on the oxidizing/reducing agent...

. Nitrite is also highly toxic to fish in high concentrations. Another type of bacteria, genus Nitrospira, on–converts nitrite into less–toxic nitrate

Nitrate

The nitrate ion is a polyatomic ion with the molecular formula NO and a molecular mass of 62.0049 g/mol. It is the conjugate base of nitric acid, consisting of one central nitrogen atom surrounded by three identically-bonded oxygen atoms in a trigonal planar arrangement. The nitrate ion carries a...

. (Nitrobacter
Nitrobacter
Nitrobacter is genus of mostly rod-shaped, gram-negative, and chemoautotrophic bacteria.Nitrobacter plays an important role in the nitrogen cycle by oxidizing nitrite into nitrate in soil...

bacteria were previously believed to fill this role, and appear in "jump start" kits. While biologically they could theoretically fill the same niche as Nitrospira, it has recently been found that Nitrobacter are not present in detectable levels in established aquaria, while Nitrospira are plentiful.) This process is known in the aquarium hobby as the nitrogen cycle

Nitrogen cycle

.

Aquatic plants also metabolize ammonia and nitrate, using it to build biomass

Biomass

Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....

. However, this is only temporary, as the plants release nitrogen back into the water when older leaves die off and decompose.

Maintaining the nitrogen cycle

Although called the nitrogen "cycle" by hobbyists, in aquaria the cycle is not complete: nitrogen must be added (usually indirectly through food) and nitrates must be removed at the end. Nitrogen bound up in plant matter is removed when the plant grows too large.

Hobbyist aquaria typically do not have the requisite bacteria needed to detoxify nitrogen waste. This problem is most often addressed through filtration

Filtration

Filtration is commonly the mechanical or physical operation which is used for the separation of solids from fluids by interposing a medium through which only the fluid can pass...

.
Activated carbon

Activated carbon

Activated carbon, also called activated charcoal, activated coal or carbo activatus, is a form of carbon that has been processed to make it extremely porous and thus to have a very large surface area available for adsorption or chemical reactions.The word activated in the name is sometimes replaced...

filters absorb nitrogen compounds and other toxin

Toxin

A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...

s from the water.

Biological filters provide a medium specially designed for colonization

Colony (biology)

In biology, a colony reference to several individual organisms of the same species living closely together, usually for mutual benefit, such as stronger defense or the ability to attack bigger prey. Some insects live only in colonies...

by the desired nitrifying bacteria. Activated carbon and other substances, such as ammonia absorbing resin

Resin

Resin in the most specific use of the term is a hydrocarbon secretion of many plants, particularly coniferous trees. Resins are valued for their chemical properties and associated uses, such as the production of varnishes, adhesives, and food glazing agents; as an important source of raw materials...

s, stop working when their pores fill, so these components have to be replaced with fresh stocks periodically.

New aquaria often have problems associated with the nitrogen cycle due to insufficient beneficial bacteria, which is known as "New Tank Syndrome". Therefore, new tanks have to mature before stocking them with fish. There are three basic approaches to this: the fishless cycle, the silent cycle, and slow growth.

Tanks undergoing a "fishless cycle" have no fish. Instead, the keeper adds ammonia to feed the bacteria. During this process, ammonia

Ammonia

, nitrite

Nitrite

, and nitrate

Nitrate

levels measure progress.

The "silent cycle" involves adding fast-growing plant

Plant

Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

s and relying on them to consume the nitrogen

Nitrogen

, filling in for the bacteria work until their number increases. Anecdotal reports indicate that such plants can consume nitrogenous waste so efficiently that the ammonia and nitrite spikes that occur in more traditional cycling methods are greatly reduced or indetectable.

"Slow growth" entails slowly increasing the fish population over 6 to 8 weeks, giving bacteria time to grow and reach a balance with the increasing waste production.

The largest bacterial populations inhabit the filter; efficient filtration is vital. Sometimes, simply cleaning the filter is enough to seriously disturb the aquarium's balance. Best practice

Best practice

A best practice is a method or technique that has consistently shown results superior to those achieved with other means, and that is used as a benchmark...

is to flush mechanical filters using compatible water to dislodge organic materials, while preserving bacteria populations. Another safe practice involves cleaning only one half of the filter media every time the filter or filters are serviced to allow the remaining bacteria to repopulate the cleaned half.

Tank capacity

Biological loading is a measure of the burden placed on the aquarium ecosystem by its living inhabitants. Higher biological loading represents a more complicated ecology, which makes equilibrium easier to perturb. The surface area

Surface area

Surface area is the measure of how much exposed area a solid object has, expressed in square units. Mathematical description of the surface area is considerably more involved than the definition of arc length of a curve. For polyhedra the surface area is the sum of the areas of its faces...

of water exposed to air limits dissolved oxygen

Oxygen saturation

Oxygen saturation or dissolved oxygen is a relative measure of the amount of oxygen that is dissolved or carried in a given medium. It can be measured with a dissolved oxygen probe such as an oxygen sensor or an optode in liquid media, usually water.It has particular significance in medicine and...

.The population of nitrifying bacteria is limited by the available physical space.

Tank size

Fish capacity is a function of aquarium size. Limiting factor

Limiting factor

A limiting factor or limiting resource is a factor that controls a process, such as organism growth or species population, size, or distribution. The availability of food, predation pressure, or availability of shelter are examples of factors that could be limiting for an organism...

s include the availability of oxygen

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

in the water and the rate at which the filter

Filter

- Chemistry, engineering and materials :In chemistry, engineering, or household usage, a device to separate mixtures. See:* Filter , critical components of both freshwater and marine aquaria...

can process waste. Aquarists apply rules of thumb estimating appropriate population size; the examples below are for small freshwater fish. Larger freshwater fish and most marine fishes need much more generous allowances. Some aquarists claim that increasing water depth beyond some relatively shallow minimum does not affect capacity.

1.5 litres of water for each centimetre of fish length (1 gallon per inch).
30 square centimetres of surface area per centimetre of fish length (12 square inches per inch).

Experienced aquarists warn against mechanically applying these rules because they do not consider other important issues such as growth rate, activity level, social behavior, and so on. Once the tank nears capacity, best practice is to add the remaining fish over a period of time while monitoring water quality.

The capacity can be improved by surface movement and water circulation such as through aeration, which not only improves oxygen exchange, but also the decomposition of waste materials.

Other factors

Other variables affect tank capacity. Smaller fish consume more oxygen per unit of body weight than larger fish. Labyrinth fish

Anabantoidei

The Anabantoidei is a suborder of perciform ray-finned freshwater fish distinguished by their possession of a lung-like labyrinth organ, which enables them to breathe air. The fish in the Anabantoidei suborder are known as anabantoids or labyrinth fish...

can breathe atmospheric oxygen and need less surface area (however, some are territorial, and do not tolerate crowding). Barbs require more surface area than tetra

Tetra

s of comparable size. The presence of waste materials presents itself as a variable as well. Decomposition consumes oxygen, reducing the amount available for fish.
Oxygen dissolves less readily in warmer water, while warmer water temperature increase fish activity levels, which in turn consume more oxygen.

Fishkeeping industry

Worldwide, the fishkeeping hobby is a multi-billion dollar industry. The United States is the largest market, followed by Europe and Japan. In 1993 the United States Census Bureau

United States Census Bureau

The United States Census Bureau is the government agency that is responsible for the United States Census. It also gathers other national demographic and economic data...

found that 10.6% of U.S. households owned ornamental freshwater or saltwater fish, with an average of 8.8 fish per household. In 1993, the retail value of the fish hobby in the United States was US$910 million. In 2002, census data indicated that aquarium products and fished accounted for USD684 million dolllars.

From 1989 to 1992, almost 79% of all U.S. ornamental fish imports came from Southeast Asia

Southeast Asia

Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...

and Japan. Singapore, Thailand, the Philippines, Hong Kong, and Indonesia were the top five exporting nations. South America was the second largest exporting region, accounting for 14% of the total annual value. Colombia, Brazil and Peru were the major suppliers.

Approximately 201 million fish worth $44.7 million were imported into the United States in 1992. These fish comprised 1,539 different species

Species

; 730 freshwater

Freshwater

species, and 809 saltwater

Seawater

species. Freshwater fish accounted for approximately 96% of the total volume and 80% of the total import value. Only 32 species had import values over $10,000. The top species were freshwater and accounted for 58% of the total imported value. The top imported species are the guppy

Guppy

, neon tetra

Neon tetra

The neon tetra is a freshwater fish of the characin family of order Characiformes. The type species of its genus, it is native to blackwater or clearwater streams in southeastern Colombia, eastern Peru, and western Brazil, including the tributaries of the Solimões where the water is between...

, platy

Southern platyfish

The southern platyfish, common platy or moonfish is a species of freshwater fish in family Poecilidae of order Cyprinodontiformes. A live-bearer, it is closely related to the green swordtail and can interbreed with it...

, betta

Betta

Betta is a large genus of small, often colorful, freshwater ray-finned fishes in the gourami family . The type species is B. picta, the spotted betta.By far the best known Betta species, however, is B...

, Chinese algae eater

Gyrinocheilus

Gyrinocheilus, also Chinese algae eater or sucking loach, is the single genus in the family Gyrinocheilidae, a family of small Southeast Asian cypriniform fishes that live in fast-flowing freshwater mountain streams...

, and goldfish

Goldfish

The goldfish is a freshwater fish in the family Cyprinidae of order Cypriniformes. It was one of the earliest fish to be domesticated, and is one of the most commonly kept aquarium fish....

.
Given 91.9 million total US households in 1990, 9.7 million are fishkeepers. 8.8 fish per household implies a total aquarium fish population of approximately 85.7 million, suggesting that the US aquarium fish population turns over more than 2.3 times per year, counting only imported fish.

Historically, fish and plants for the first modern aquaria were gathered from the wild and transported (usually by ship) to Europea and America. During the early 20th century many species of small colourful tropical fish

Tropical fish

were exported from Manaus, Brazil; Bangkok, Thailand; Jakarta, Indonesia; the Netherlands Antilles; Kolkata, India; and other tropical countries. Import of wild fish, plants, and invertebrates for aquaria continues today around the world. Many species have not been successfully bred in captivity. In many developing countries, locals survive by collecting specimens for the aquarium trade., and continue to introduce new species to the market.

Fish breeding

Fish breeding is a challenge that attracts many aquarists. While some species reproduce freely in community tanks, most require special conditions, known as spawning triggers

Spawning triggers

Spawning triggers are environmental cues that cause fish to breed. Most commonly they involve sudden changes in the environment, such as changes in temperature, salinity, and the abundance of food. Catfish of the genus Corydoras, for example, spawn immediately after heavy rain, the specific cues...

before they will breed. The majority of fish lay eggs, known as spawning

Spawn (biology)

Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...

, and the juvenile fish that emerge are very small and need tiny live food or substitutes to survive. A fair number of popular aquarium fish are livebearers

Live-bearing aquarium fish

Live-bearing aquarium fish, often simply called livebearers, are fish that retain the eggs inside the body and give birth to live, free-swimming young.-Common aquarium livebearers:...

which produce a small number of relatively large offspring. These usually take ground flake food straight away.

Animal welfare

A properly maintained aquarium allows fish to socialize with their own species and in many cases breed successfully. This is in marked contrast to the conditions of larger animals like cats and dogs, which are often kept alone and neutered

Neutering

Neutering, from the Latin neuter , is the removal of an animal's reproductive organ, either all of it or a considerably large part. The process is often used in reference to males whereas spaying is often reserved for females. Colloquially, both terms are often referred to as fixing...

in an environment different from what they would experience in the wild. However, fish are often maintained in inadequate conditions. Therefore they live short lives and never breed.

Inexperienced aquarists often keep too many fish in one tank, or add fish too quickly into an immature aquarium, killing many of them.This has given the hobby a bad reputation among some animal welfare groups, such as PETA

People for the Ethical Treatment of Animals

People for the Ethical Treatment of Animals is an American animal rights organization based in Norfolk, Virginia, and led by Ingrid Newkirk, its international president. A non-profit corporation with 300 employees and two million members and supporters, it claims to be the largest animal rights...

, who accuse aquarists of treating aquarium fish as cheap toys to be replaced when they die.

Goldfish and bettas

Siamese fighting fish

The Siamese fighting fish , also known as the betta , is a popular species of freshwater aquarium fish. The name of the genus is derived from ikan bettah, taken from a local dialect of Malay...

in particular have often been kept in small bowls or aquaria that are too small for their needs. In some cases fish have been installed in all sorts of inappropriate objects such as the "AquaBabies Micro Aquaria", "Bubble Gear Bubble Bag", and "Betta in a Vase", all of which house live fish in unfiltered and insufficient water. The latter is sometimes marketed as a complete ecosystem because a plant is included in the neck of the vase. Some sellers claim the fish eat the plant roots. However, betta

Betta

s are carnivorous

Carnivore

A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...

and need live food or pellet foods. They cannot survive on plant roots. Another problem is that the plant sometimes blocks the betta's passage to the water surface. They are labyrinth fish

Anabantoidei

, and need to breathe at the surface to avoid suffocation.

Such products are aimed at people looking for a novelty gift. Aquarists actively condemn them. Similarly, the awarding of goldfish as prizes at funfair

Funfair

A funfair or simply "fair" is a small to medium sized travelling show primarily composed of stalls and other amusements. Larger fairs such as the permanent fairs of cities and seaside resorts might be called a fairground, although technically this should refer to the land where a fair is...

s is traditional in many parts of the world, but has been criticized by aquarists and activists as cruel and irresponsible. The United Kingdom outlawed live-animal prizes such as goldfish in 2004.

The use of live prey to feed carnivorous fish such as piranha

Piranha

A piranha or piraña is a member of family Characidae in order Characiformes, an omnivorous freshwater fish that inhabits South American rivers. In Venezuela, they are called caribes...

s also draws criticism.

Fish modification

Modifying fish to make them more attractive as pets is increasingly controversial. Historically, artificially dyeing

Painted fish

The term painted fish refers to ornamental aquarium fish which have been artificially coloured to appeal to consumers. This artificial colouring, also known as juicing, is achieved by a number of methods, such as injecting the fish with a hypodermic syringe containing bright fluorescent colour dye,...

fish was common. Glassfish

Ambassidae

The Asiatic glassfishes are a family, Ambassidae, of freshwater and marine fishes in the order Perciformes. The species in the family are native to the waters of Asia and Oceania and the Indian and western Pacific Oceans. The family includes eight genera and about fifty species.The family was...

in particular were often injected with fluorescent dyes. The major British fishkeeping magazine, Practical Fishkeeping

Practical Fishkeeping

Practical Fishkeeping is the United Kingdom's best-selling aquarium magazine. It is published every four weeks by Bauer...

, has been effective in its campaign to remove these fish from the market by educating retailers and aquarists to the cruelty and health risks involved.

In 2006, Practical Fishkeeping

Practical Fishkeeping

Practical Fishkeeping is the United Kingdom's best-selling aquarium magazine. It is published every four weeks by Bauer...

published an article exposing the techniques for performing cosmetic surgery

Plastic surgery

Plastic surgery is a medical specialty concerned with the correction or restoration of form and function. Though cosmetic or aesthetic surgery is the best-known kind of plastic surgery, most plastic surgery is not cosmetic: plastic surgery includes many types of reconstructive surgery, hand...

on aquarium fish, without anaesthesia, as described by Singapore

Singapore

Singapore , officially the Republic of Singapore, is a Southeast Asian city-state off the southern tip of the Malay Peninsula, north of the equator. An island country made up of 63 islands, it is separated from Malaysia by the Straits of Johor to its north and from Indonesia's Riau Islands by the...

an fishkeeping magazine Fish Love Magazine. The tail is cut off and dye is injected into the body. The piece also included the first documented evidence to demonstrate that parrot cichlids are injected with coloured dye. Hong Kong suppliers were offering a service in which fish could be tattoo

Tattoo

A tattoo is made by inserting indelible ink into the dermis layer of the skin to change the pigment. Tattoos on humans are a type of body modification, and tattoos on other animals are most commonly used for identification purposes...

ed with company logos or messages using a dye laser

Dye laser

A dye laser is a laser which uses an organic dye as the lasing medium, usually as a liquid solution. Compared to gases and most solid state lasing media, a dye can usually be used for a much wider range of wavelengths. The wide bandwidth makes them particularly suitable for tunable lasers and...

; such fishes have been sold in the UK under the name of Kaleidoscope gourami and Striped parrot cichlid. Some people give their fish body piercing

Body piercing

Body piercing, a form of body modification, is the practice of puncturing or cutting a part of the human body, creating an opening in which jewelry may be worn. The word piercing can refer to the act or practice of body piercing, or to an opening in the body created by this act or practice...

s.

Hybrid fish such as flowerhorn cichlids and parrot cichlids are highly controversial. Parrot cichlids in particular have a very unnatural shape that prevents them from swimming properly and makes it difficult for them to engage in normal feeding and social behaviors. The biggest concern with hybrids is that they may be bred with native species, making it difficult for hobbyists to identify and breed particular species. This is especially important to hobbyists who shelter species that are rare or extinct in the wild. Extreme mutations have been selected for by some breeders; some fancy goldfish

Goldfish

The goldfish is a freshwater fish in the family Cyprinidae of order Cypriniformes. It was one of the earliest fish to be domesticated, and is one of the most commonly kept aquarium fish....

varieties in particular have features that prevent the fish from swimming, seeing, or feeding properly.

Genetically modified

Genetic engineering

Genetic engineering, also called genetic modification, is the direct human manipulation of an organism's genome using modern DNA technology. It involves the introduction of foreign DNA or synthetic genes into the organism of interest...

fish such as the GloFish

GloFish

The GloFish is a patented and trademarked brand of genetically modified fluorescent zebrafish with bright red, green, orange-yellow, blue, and purple fluorescent colors...

are likely to become increasingly available, particularly in the United States and Asia. Although GloFish are said to be unharmed by their genetic modifications, they remain illegal in many places, including the European Union, though at least some have been smuggled

Smuggling

Smuggling is the clandestine transportation of goods or persons, such as out of a building, into a prison, or across an international border, in violation of applicable laws or other regulations.There are various motivations to smuggle...

into the EU, most likely from Taiwan, via the Czech Republic.

Conservation

The two main sources of fish for aquaria are from capture in the wild or captive breeding. United Nations studies show that more than 90% of freshwater

Freshwater

aquarium fish are captive–bred, while virtually all marine

Marine (ocean)

Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

fish and invertebrates are caught. The few marine species bred in captivity supplement but rarely replace the trade in wild-caught specimens. Wild-caught animals provide valuable income for people in regions lacking other high-value export

Export

The term export is derived from the conceptual meaning as to ship the goods and services out of the port of a country. The seller of such goods and services is referred to as an "exporter" who is based in the country of export whereas the overseas based buyer is referred to as an "importer"...

s.

Marine fish are typically less resilient during transport than freshwater fish, and relatively large numbers of them die before they reach the aquarist. Although the aquarium trade probably represents a minor threat to coral reefs compared to habitat destruction, fishing for food, and climate change, it is a booming trade and may be a serious problem in specific locations such as the Philippines and Indonesia where most collecting is done. Catching fish in the wild can reduce their population sizes, placing them in danger of extinction in collecting areas, as has been observed with the dragonet

Dragonet

Dragonets are small, perciform, marine fish of the diverse family Callionymidae . Found mainly in the tropical waters of the western Indo-Pacific, the family contains approximately 186 species in 18 genera. The Draconettidae may be considered a sister family, whose members are very much alike,...

Synchiropus splendidus
Mandarinfish
The Mandarinfish or Mandarin dragonet , is a small, brightly-colored member of the dragonet family, which is popular in the saltwater aquarium trade...

.

Collecting

In theory, reef fish should be a good example of a renewable resource

Renewable resource

A renewable resource is a natural resource with the ability of being replaced through biological or other natural processes and replenished with the passage of time...

that encourages fishermen to maintain the integrity and diversity of the natural habitat: more and better fish can be exported from pristine habitats than those that have been polluted or over-harvested. However, this has not been the case in similar industries such as fur trapping, logging

Logging

Logging is the cutting, skidding, on-site processing, and loading of trees or logs onto trucks.In forestry, the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard...

, or fishing

Fishing industry

The fishing industry includes any industry or activity concerned with taking, culturing, processing, preserving, storing, transporting, marketing or selling fish or fish products....

that experience the tragedy of the commons
Tragedy of the commons
The tragedy of the commons is a dilemma arising from the situation in which multiple individuals, acting independently and rationally consulting their own self-interest, will ultimately deplete a shared limited resource, even when it is clear that it is not in anyone's long-term interest for this...

.

Fish are caught by net, trap, or cyanide. Collecting expeditions can be lengthy and costly, and are not always successful. Fish can also be injured during collection and/or shipping; mortality rate

Mortality rate

Mortality rate is a measure of the number of deaths in a population, scaled to the size of that population, per unit time...

s during shipping are high. Many others are weakened by stress

Stress (biology)

Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance...

and become diseased.

Other problems include the poisoning of coral reef

Coral reef

s and non-target species, the depletion of rare species from their natural habitat, and ecosystem degradation from large scale removal of key species. Additionally, destructive fishing techniques

Unsustainable fishing methods

Unsustainable fishing methods are ways of catching wild fish that are not considered sustainable in the long term. This could be because they threaten the fish stock itself by overfishing, or because they threaten the environment the fish need to thrive...

concern environmentalists and hobbyists alike. There has been a concerted movement to captive breeding and certification programs for wild-caught fish. Two thirds of American marine aquarists surveyed in 1997 preferred farmed coral, and over 80% think that only sustainably caught or farmed fish should be traded.

Cyanide

A cyanide is a chemical compound that contains the cyano group, -C≡N, which consists of a carbon atom triple-bonded to a nitrogen atom. Cyanides most commonly refer to salts of the anion CN−. Most cyanides are highly toxic....

is a poison that stuns and immobilizes fish. Fishers put cyanide in the ocean, to ease the process of netting them. It can irreversibly damage or kill the target fish, as well as other fish, mammals, reptiles or invertebrates that are left behind. Some UK-based wholesalers advertise that they avoid cyanide-caught animals. In the Philippines, overfishing and cyanide caused a drastic decline in aquarium fish, leading the country away from cyanide and towards netting healthy animals. Cyanide is also often used for collecting freshwater species, especially in muddy water with lots of vegetation, which complicates catching small and fast moving fish.

Captive breeding and aquaculture

Since the Siamese fighting fish

Siamese fighting fish

The Siamese fighting fish , also known as the betta , is a popular species of freshwater aquarium fish. The name of the genus is derived from ikan bettah, taken from a local dialect of Malay...

(Betta splendens) was first successfully bred in France in 1893, captive spawning and brooding techniques used in aquaculture

Aquaculture

Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...

have slowly improved. Captive breeding for aquaria is concentrated in southern Florida, Singapore, Hong Kong and Bangkok, with smaller industries in Hawaii and Sri Lanka. Captive breeding of marine organisms has been in development since the mid-1990s. Breeding for freshwater species is more advanced than for saltwater

Seawater

species. Currently, only a few captive-bred marine species are in the trade, including clownfish

Clownfish

Clownfish or anemonefish are fishes from the subfamily Amphiprioninae in the family Pomacentridae. Twenty-eight species are recognized, one in the genus Premnas, while the remaining are in the genus Amphiprion. In the wild they all form symbiotic mutualisms with sea anemones...

, damselfish

Damselfish

Damselfish comprise the family Pomacentridae except those of the genera Amphiprion and Premnas. They can grow up to long. While most are marine, a few species inhabit the lower stretches of rivers in freshwater. Damselfish usually have bright colors. in tropical coral reefs, and many of those are...

, and dwarf angelfish

Centropyge

Centropyge is a genus of marine angelfishes. The genus is the largest within the Pomacanthid family, comprising over 30 described species. Species in this group do not exceed 15 cm in length and live in haremic structures with one dominant male and multiple females...

.

Aquaculture can help in lessening the impacts on wild stocks, either by using cultivated organisms for sale or by releasing them to replenish wild stocks. Breeding programs help preserve species that have become rare or extinct in the wild, most notably the Lake Victoria

Lake Victoria

Lake Victoria is one of the African Great Lakes. The lake was named for Queen Victoria of the United Kingdom, by John Hanning Speke, the first European to discover this lake....

cichlid

Cichlid

s.

Some species have also become important as laboratory animals. Cichlids and poecilids

Poecilia

Poecilia is a genus of euryhaline brackish water fish in family Poeciliidae of order Cyprinodontiformes. The type species is P. vivipara. Live-bearers, the Poecilia species are collectively known as mollies, with the exception of Endler's livebearer and the famous guppy...

are especially important for studies on learning, mating, and social behavior. Hobbyists also keep and observe many fishes not otherwise studied, and thereby provide valuable ecological and behavioral data.

Captive breeding has reduced prices for hobbyists, but cultured animals remain more expensive. Selective breeding has also led to wider intra–species variation, creating more diverse commercial stocks.

Invasive species

Serious problems can occur when fish originally raised in ponds or aquaria

Aquarium

are released into the wild. While tropical

Tropics

fish do not survive in temperate climates, they can thrive in waters that are similar to their native habitat. Non–native species that become established are called exotic species

Introduced species

An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...

. Freshwater examples include various cichlids in Florida, goldfish

Goldfish

The goldfish is a freshwater fish in the family Cyprinidae of order Cypriniformes. It was one of the earliest fish to be domesticated, and is one of the most commonly kept aquarium fish....

in temperate waters, and South American suckermouth catfishes

Loricariidae

Loricariidae is the largest family of catfish , with almost 700 species and new species being described each year. Loricariids originate from fresh water habitats of Costa Rica, Panama, and tropical and subtropical South America. These fish are noted for the bony plates covering their bodies and...

in warm waters around the world. Invasive species

Invasive species

"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....

can seriously disrupt their new homes by preying on, or competing with, native species. Many marine fish have also been introduced into non-native waters, disrupting the local habitat.

Humane treatment

In January 2011 the Maui

Maui

The island of Maui is the second-largest of the Hawaiian Islands at and is the 17th largest island in the United States. Maui is part of the state of Hawaii and is the largest of Maui County's four islands, bigger than Lānai, Kahoolawe, and Molokai. In 2010, Maui had a population of 144,444,...

County Council just passed measure requiring the aquarium

Aquarium

fishery

Fisheries management

Fisheries management draws on fisheries science in order to find ways to protect fishery resources so sustainable exploitation is possible. Modern fisheries management is often referred to as a governmental system of appropriate management rules based on defined objectives and a mix of management...

to adopt humane practices for preparing fish for transport to market. The regulations control harvesting and shipping practices, including prohibiting clipping the fins on fish to protect the plastic shipping bags, outlawing puncturing swim bladders that fish use to regulate their buoyancy, which enabled divers to rapidly surface and prohibiting "starving" the fish which permitted smaller shipping bags without killing the fish with their own waste. The measure also requires that shippers file mortality reports on the animals they ship.

External links

The Aquarium Wiki Encyclopaedia - The Nitrogen Cycle.

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.

Types of fishkeeping systems

Freshwater

Saltwater

Brackish water

The origins of fishkeeping

Aquarium maintenance

Water conditions

Nitrogen cycle

The process

Maintaining the nitrogen cycle

Tank capacity

Tank size

Other factors

Fishkeeping industry

Fish breeding

Animal welfare

Fish modification

Conservation

Collecting

Cyanide

Captive breeding and aquaculture

Invasive species

Humane treatment

Further reading

External links