Fish diseases
Encyclopedia
Ornamental fish kept in aquarium
s are susceptible to numerous disease
s. The study of fish diseases has remained a rudimentary branch of veterinary medicine
. Due to their generally small size and the low cost of replacing diseased or dead fish, the cost of testing and treating diseases is often seen as more trouble than the value of the fish.
Due to the artificially limited volume of water and high concentration of fish in most aquarium
tanks, communicable diseases often affect most or all fish in a tank. An improper nitrogen cycle
, inappropriate aquarium plants and potentially harmful freshwater invertebrate
s can directly harm or add to the stresses
on ornamental fish in a tank. Despite this, many diseases in captive fish can be avoided or prevented through proper water conditions and a well-adjusted ecosystem
within the tank.
Diseases can have a variety of causes, including bacteria
l infection
s from an external source
such as Pseudomonas fluorescens
(causing Fin rot
and Fish Dropsy
), fungal
infections (Saprolegnia
), Mould infections (Oomycete and Saprolegnia
), parasitic disorders (Gyrodactylus salaris
, Ichthyophthirius multifiliis, Cryptocaryon
, Oodinium
causing velvet disease
, Brooklynella hostilis
, head and lateral line erosion, Glugea
, Ceratomyxa shasta
, Kudoa thyrsites
, Tetracapsuloides bryosalmonae
, Ceratomyxa shasta
, leech
es, nematode
, Trematoda
, Platyhelminthes and fish louse), viral
disorders, metabolic disorders, inappropriate water conditions (insufficient aeration
, pH
, water hardness
, temperature and ammonia poisoning
) and malnutrition.
new additions before adding them to an established tank, and discarding water from external sources rather than mixing it with clean water. Similarly, foods for herbivorous fish such as lettuce
or cucumber
s should be washed before being placed in the tank. Containers that do not have water filters
or pump
s to circulate water can also increase stress to fish. Other stresses on fish and tanks can include certain chemicals, soap
s and detergent
s, and impacts to tank walls causing shock wave
s that can damage fish.
and fungicide
, and will not damaging beneficial bacteria, though ordinary table salt may contain additives which can harm fish. Alternatives include aquarium salt, Kosher salt
or rock salt. Gradually raising the temperature of the tank may kill certain parasites, though some diseased fish may be harmed and certain species can not tolerate high temperatures. Aeration is necessary since less oxygen is dissolved in warm water.
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...
s are susceptible to numerous disease
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
s. The study of fish diseases has remained a rudimentary branch of veterinary medicine
Veterinary medicine
Veterinary Medicine is the branch of science that deals with the prevention, diagnosis and treatment of disease, disorder and injury in non-human animals...
. Due to their generally small size and the low cost of replacing diseased or dead fish, the cost of testing and treating diseases is often seen as more trouble than the value of the fish.
Issues in diagnosis and treatment
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...
tanks, communicable diseases often affect most or all fish in a tank. An improper 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...
, inappropriate aquarium plants and potentially harmful freshwater invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s can directly harm or add to the stresses
Stress (medicine)
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...
on ornamental fish in a tank. Despite this, many diseases in captive fish can be avoided or prevented through proper water conditions and a well-adjusted 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....
within the tank.
Etiology
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...
l infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
s from an external source
External bacterial infection (fish)
-Symptoms:There are a great deal of possible symptoms associated with this disorder. There may be spots on the body which appear red or orange. Watch for red streaks on the surface on the body. Dropsy is also a sign of a bacterial disorder. "False fungal infections" look like fungus but is...
such as Pseudomonas fluorescens
Pseudomonas fluorescens
Pseudomonas fluorescens is a common Gram-negative, rod-shaped bacterium. It belongs to the Pseudomonas genus; 16S rRNA analysis has placed P. fluorescens in the P. fluorescens group within the genus, to which it lends its name....
(causing Fin rot
Fin rot
Fin rot is a symptom of disease or the actual disease in fish. This is a disease which is most often observed in aquaria and aquaculture, but can also occur in natural populations....
and Fish Dropsy
Fish dropsy
Dropsy is a common disease among fresh-water aquarium fish. It is characterized by a swollen or hollow abdomen. The name is from an old name for Edema in humans. -Symptoms:...
), fungal
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...
infections (Saprolegnia
Saprolegnia
Saprolegnia is a genus of freshwater mould often called a "cotton mould" because of the characteristic white or grey fibrous patches it forms. Current taxonomy puts Saprolegnia as a genus of the heterokonts in the order Saprolegniales.-Habits:...
), Mould infections (Oomycete and Saprolegnia
Saprolegnia
Saprolegnia is a genus of freshwater mould often called a "cotton mould" because of the characteristic white or grey fibrous patches it forms. Current taxonomy puts Saprolegnia as a genus of the heterokonts in the order Saprolegniales.-Habits:...
), parasitic disorders (Gyrodactylus salaris
Gyrodactylus salaris
Gyrodactylus salaris is a small monogenean ectoparasite which mainly lives on the skin of freshwater fish, especially Atlantic salmon. This species is a leech-like parasite that has been implicated in some diminution of Atlantic salmon populations in the Norwegian fjords. Its common name is Salmon...
, Ichthyophthirius multifiliis, Cryptocaryon
Cryptocaryon
Cryptocaryon irritans is a species of ciliate protozoa that parasitizes marine fish, and is one of the most common causes of disease in marine aquaria.-Taxonomy:...
, Oodinium
Oodinium
Oödinium is a genus of microscopic parasitic dinoflagellates. They live off salt and fresh water fish, causing a type of fish velvet disease . One species has also been recorded on various cnidarians .The host typically develops small yellow or gold dust scattered on its head, fins and body...
causing velvet disease
Velvet (fish disease)
Velvet disease, also called gold dust disease is a fish disease caused by the dinoflagellate parasites of the genus Piscinoodinium, which gives the fish a dusty, slimy look. The disease occurs most commonly in tropical and marine aquaria.-Life cycle:The single-celled parasite's life cycle can be...
, Brooklynella hostilis
Brooklynella hostilis
Brooklynella hostilis is a marine parasite that causes a condition known as "Clownfish disease". It is known to be found in marine aquariums....
, head and lateral line erosion, Glugea
Glugea
Glugea is a genus of microsporidian parasites, predominantly infecting fish.Species include* Glugea anomala* Glugea atherinae* Glugea capverdensis - a parasite of the fish Myctophum punctatum...
, Ceratomyxa shasta
Ceratomyxa shasta
Ceratomyxa shasta is a myxosporean parasite that infects salmonid fish on the Pacific coast of North America. It was first observed at the Crystal Lake Hatchery, Shasta County, California, and has now been reported from Idaho, Oregon, Washington, British Columbia and Alaska .-Life history:In...
, Kudoa thyrsites
Kudoa thyrsites
Kudoa thrysites is a myxosporean parasite of marine fishes. It has a worldwide distribution, and infects a wide range of host species. This parasite is responsible for causing economic losses to the fisheries sector, by causing post-mortem "myoliquefaction", a softening of the flesh to such an...
, Tetracapsuloides bryosalmonae
Tetracapsuloides bryosalmonae
Tetracapsuloides bryosalmonae is a myxozoan parasite of salmonid fishes, which causes Proliferative kidney disease , one of the most serious parasitic diseases of salmonid populations in Europe and North America, which causes losses of up to 90% in infected populations.-Taxonomy:Until the late...
, Ceratomyxa shasta
Ceratomyxa shasta
Ceratomyxa shasta is a myxosporean parasite that infects salmonid fish on the Pacific coast of North America. It was first observed at the Crystal Lake Hatchery, Shasta County, California, and has now been reported from Idaho, Oregon, Washington, British Columbia and Alaska .-Life history:In...
, leech
Leech
Leeches are segmented worms that belong to the phylum Annelida and comprise the subclass Hirudinea. Like other oligochaetes such as earthworms, leeches share a clitellum and are hermaphrodites. Nevertheless, they differ from other oligochaetes in significant ways...
es, nematode
Nematode
The nematodes or roundworms are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 28,000 have been described, of which over 16,000 are parasitic. It has been estimated that the total number of nematode...
, Trematoda
Trematoda
Trematoda is a class within the phylum Platyhelminthes that contains two groups of parasitic flatworms, commonly referred to as "flukes".-Taxonomy and biodiversity:...
, Platyhelminthes and fish louse), viral
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
disorders, metabolic disorders, inappropriate water conditions (insufficient aeration
Aeration
Aeration is the process by which air is circulated through, mixed with or dissolved in a liquid or substance.-Aeration of liquids:-Methods:Aeration of liquids is achieved by:...
, pH
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...
, water hardness
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...
, temperature and ammonia poisoning
Ammonia Poisoning
Ammonia poisoning is a common fish disease in new aquariums, especially when immediately stocked to full capacity. Ideally, the level of ammonia and ammonium compounds should be zero. Although trace amounts are generally harmless, they can still lead to problems over time. Understanding the...
) and malnutrition.
Prevention
Disease cures are almost always more expensive and less effective than simple prevention measures. Often precautions involve maintaining a stable aquarium that is adjusted for the specific species of fish that are kept and not over-crowding a tank or over-feeding the fish. Common preventive strategies include avoiding the introduction of infected fish, invertebrates or plants by quarantiningQuarantine
Quarantine is compulsory isolation, typically to contain the spread of something considered dangerous, often but not always disease. The word comes from the Italian quarantena, meaning forty-day period....
new additions before adding them to an established tank, and discarding water from external sources rather than mixing it with clean water. Similarly, foods for herbivorous fish such as lettuce
Lettuce
Lettuce is a temperate annual or biennial plant of the daisy family Asteraceae. It is most often grown as a leaf vegetable. It is eaten either raw, notably in salads, sandwiches, hamburgers, tacos, and many other dishes, or cooked, as in Chinese cuisine in which the stem becomes just as important...
or cucumber
Cucumber
The cucumber is a widely cultivated plant in the gourd family Cucurbitaceae, which includes squash, and in the same genus as the muskmelon. The plant is a creeping vine which bears cylindrical edible fruit when ripe. There are three main varieties of cucumber: "slicing", "pickling", and...
s should be washed before being placed in the tank. Containers that do not have water filters
Filter (water)
A water filter removes impurities from water by means of a fine physical barrier, a chemical process or a biological process. Filters cleanse water to various extents for irrigation, drinking water, aquariums, and swimming pools.-Methods of filtration:...
or 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...
s to circulate water can also increase stress to fish. Other stresses on fish and tanks can include certain chemicals, soap
Soap
In chemistry, soap is a salt of a fatty acid.IUPAC. "" Compendium of Chemical Terminology, 2nd ed. . Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford . XML on-line corrected version: created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN...
s and detergent
Detergent
A detergent is a surfactant or a mixture of surfactants with "cleaning properties in dilute solutions." In common usage, "detergent" refers to alkylbenzenesulfonates, a family of compounds that are similar to soap but are less affected by hard water...
s, and impacts to tank walls causing shock wave
Shock wave
A shock wave is a type of propagating disturbance. Like an ordinary wave, it carries energy and can propagate through a medium or in some cases in the absence of a material medium, through a field such as the electromagnetic field...
s that can damage fish.
Treatment
In some cases the causes of an infection or disease will be obvious (such as fin rot), though in other cases it may be due to water conditions, requiring special testing equipment and chemicals to appropriately adjust the water. Isolating diseased fish can help prevent the spread of infection to healthy fish in the tank. This also allows the use of chemicals or drugs which may damage the nitrogen cycle, plants or chemical filtration of a properly-functioning tank. Other alternatives include short baths in a bucket that contains the treated water. Salt baths can be used as an antisepticAntiseptic
Antiseptics are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction...
and fungicide
Fungicide
Fungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals...
, and will not damaging beneficial bacteria, though ordinary table salt may contain additives which can harm fish. Alternatives include aquarium salt, Kosher salt
Kosher salt
Koshering salt, usually referred to as kosher salt in the US, is a variety of edible salt with a much larger grain size than some common table salt...
or rock salt. Gradually raising the temperature of the tank may kill certain parasites, though some diseased fish may be harmed and certain species can not tolerate high temperatures. Aeration is necessary since less oxygen is dissolved in warm water.