The tench or doctor fish (Tinca tinca) is a 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...

 and brackish water

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"...

 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...

 of the 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...

 (commonly called 'carp') family found throughout Eurasia

Eurasia

Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...

 from Western Europe

Western Europe

Western Europe is a loose term for the collection of countries in the western most region of the European continents, though this definition is context-dependent and carries cultural and political connotations. One definition describes Western Europe as a geographic entity—the region lying in the...

 including the British Isles

British Isles

The British Isles are a group of islands off the northwest coast of continental Europe that include the islands of Great Britain and Ireland and over six thousand smaller isles. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and...

 east into Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

 as far as the Ob

Ob River

The Ob River , also Obi, is a major river in western Siberia, Russia and is the world's seventh longest river. It is the westernmost of the three great Siberian rivers that flow into the Arctic Ocean .The Gulf of Ob is the world's longest estuary.-Names:The Ob is known to the Khanty people as the...

 and Yenisei River

Yenisei River

Yenisei , also written as Yenisey, is the largest river system flowing to the Arctic Ocean. It is the central of the three great Siberian rivers that flow into the Arctic Ocean...

s. It is also found in Lake Baikal

Lake Baikal

Lake Baikal is the world's oldest at 30 million years old and deepest lake with an average depth of 744.4 metres.Located in the south of the Russian region of Siberia, between Irkutsk Oblast to the northwest and the Buryat Republic to the southeast, it is the most voluminous freshwater lake in the...

. It normally inhabits slow-moving freshwater habitats, particularly lakes and lowland rivers. Also known for being a 'Lush fish'.

Ecology

The tench is most often found in still waters with a clay

Clay

Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...

 or mud

Mud

Mud is a mixture of water and some combination of soil, silt, and clay. Ancient mud deposits harden over geological time to form sedimentary rock such as shale or mudstone . When geological deposits of mud are formed in estuaries the resultant layers are termed bay muds...

dy substrate

Substrate (biology)

In biology a substrate is the surface a plant or animal lives upon and grows on. A substrate can include biotic or abiotic materials and animals. For example, encrusting algae that lives on a rock can be substrate for another animal that lives on top of the algae. See also substrate .-External...

 and abundant vegetation. This species is rare in clear waters across stony ground, and is absent altogether from fast-flowing streams. It tolerates water with a low 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...

 concentration, being found in waters where even the 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...

 cannot survive.
Tench feed mostly at night with a preference for animals, like chironomids on the bottom of eutrophic waters and snails and pea clams

Pisidium

Pisidium is a genus of very small or minute freshwater clams known as pill clams or pea clams, aquatic bivalve molluscs in the family Sphaeriidae.-Subgenera and species:Subgenera and species within the genus Pisidium include:...

 in well vegetated waters

Breeding takes place in shallow water usually among aquatic plants where the sticky green eggs can be deposited. Spawning usually occurs in summer, and as many as three hundred thousand eggs may be produced. Growth is rapid, and fish may reach a weight of 0.11 kg

Kilogram

The kilogram or kilogramme , also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram , which is almost exactly equal to the mass of one liter of water...

 (0.25 lb

Pound (mass)

The pound or pound-mass is a unit of mass used in the Imperial, United States customary and other systems of measurement...

) within the first year.

Morphology

Tench have a stocky, carp-like shape, olive-green skin, darker above and almost golden below. The caudal fin is square in shape. The other fins are distinctly rounded in shape. The mouth is rather narrow and provided at each corner with a very small barbel

Barbel (anatomy)

A barbel on a fish is a slender, whiskerlike tactile organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, sturgeon, the zebrafish and some species of shark...

. Maximum size is 70 cm, though most specimens are very much smaller. The eyes are small and red-orange in colour. Sexual dimorphism is weak, limited to the adult females having a more convex ventral profile when compared with males. Males may also possess a very thick and flattened outer ray to the ventral fins. Males are generally smaller than females but can be recognised by having more curved lower fins and noticeable muscles around the base of the fins generally absent in female.

The tench has very small scales, which are deeply imbedded in a thick skin, making it as slippery as an eel

Eel

Eels are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators...

. Folklore

Folklore

Folklore consists of legends, music, oral history, proverbs, jokes, popular beliefs, fairy tales and customs that are the traditions of a culture, subculture, or group. It is also the set of practices through which those expressive genres are shared. The study of folklore is sometimes called...

 has it that this slime cured any sick fish that rubbed against it, and from this belief arose the name doctor fish.

Golden tench

An artificially-bred variety of tench called the golden tench or schlei is a popular ornamental fish

Fishkeeping

Fishkeeping is a popular hobby concerned with keeping fish in a home aquarium or garden pond. There is also a fishkeeping industry, as a branch of agriculture.-Types of fishkeeping systems:...

 for ponds. This form varies in colour from pale gold through to red, and some fish have black or red spots on the flanks and fins. Though somewhat similar to the 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....

, because these fish have such small scales, the golden quality is rather different.

Economic significance

Tench are edible and considered to have a fine flavour, working well in recipes that would otherwise call for carp. They are an important target for coarse angler

Fisherman

A fisherman or fisher is someone who captures fish and other animals from a body of water, or gathers shellfish. Worldwide, there are about 38 million commercial and subsistence fishermen and fish farmers. The term can also be applied to recreational fishermen and may be used to describe both men...

s and are also used as fodder

Fodder

Fodder or animal feed is any agricultural foodstuff used specifically to feed domesticated livestock such as cattle, goats, sheep, horses, chickens and pigs. Most animal feed is from plants but some is of animal origin...

 for predatory species such as bass

Centrarchidae

The sunfishes are a family of freshwater ray-finned fish belonging to the order Perciformes. The type genus is Centrarchus . The family's 27 species includes many fishes familiar to North Americans, including the rock bass, largemouth bass, bluegill, pumpkinseed, and crappies...

. Tench, particularly golden tench, are also kept as ornamental fish in ponds and less frequently aquaria.

Angling

Large tench may be found in gravel pits or deep, slow-moving waters with a clayey or silty bottom and lots of aquatic vegetation.
The best methods and bait to catch Tench are float fishing and legering with a swim feeder using maggots, sweetcorn, pellets, bread and worms as hook bait and groundbait in the swimfeeder if you are not float fishing. Due to the Tench being a bottom feeder it is essential that your bait is resting on the bottom of the lake/pond/canal bed when float fishing - use a plummet to make sure your bait is resting on the bottom by an inch or two. Fish over 1 kg (2 lb) in weight are very strong fighters when caught on a rod.