The tench or doctor fish (''Tinca tinca'') is a fresh- and brackish-water fish of the order

Cypriniformes Cypriniformes is an order of ray-finned fish, including the carps, minnows, loaches, and relatives. Cypriniformes is an Order within the Superorder Ostariophysi consisting of "Carp-like" Ostariophysins. This order contains 11-12 families, ...

found throughout Eurasia from Western Europe including the British Isles east into Asia as far as the Ob and Yenisei Rivers. It is also found in

Lake Baikal Lake Baikal (, russian: Oзеро Байкал, Ozero Baykal ); mn, Байгал нуур, Baigal nuur) is a rift lake in Russia. It is situated in southern Siberia, between the federal subjects of Irkutsk Oblast to the northwest and the Repu ...

. It normally inhabits slow-moving freshwater habitats, particularly lakes and lowland rivers.B. Whitton (1982). ''Rivers, Lakes and Marshes'' p 163. Hodder & Staughton, London.

Taxonomy

The tench was formerly classified in the subfamily Leuciscinae with other Eurasian minnows, but more recent phylogenetic studies have supported it belonging to its own family Tincidae.

Ecology

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

mud A MUD (; originally multi-user dungeon, with later variants multi-user dimension and multi-user domain) is a Multiplayer video game, multiplayer Time-keeping systems in games#Real-time, real-time virtual world, usually Text-based game, text-bas ...

substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (locomotion), the surface over which an organism lo ...

and abundant vegetation.A. F. Magri MacMahon (1946). ''Fishlore'', pp 156-158. Pelican Books. This species is rare in clear waters across stony substrate, and is absent altogether from fast-flowing streams. It tolerates water with a low oxygen concentration, being found in waters where even the

carp Carp are various species of oily freshwater fish from the family Cyprinidae, a very large group of fish native to Europe and Asia. While carp is consumed in many parts of the world, they are generally considered an invasive species in parts of ...

cannot survive. Tinca tinca Prague Vltava 3

Tench feed mostly at night with a preference for animals, such as

chironomids The Chironomidae (informally known as chironomids, nonbiting midges, or lake flies) comprise a family of nematoceran flies with a global distribution. They are closely related to the Ceratopogonidae, Simuliidae, and Thaumaleidae. Many species s ...

, on the bottom of eutrophic waters and snails and pea clams 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 300,000 eggs may be produced.A. Lawrence Wells (date unknown). ''Observer Book of Freshwater Fishes'', pp 101-105. Frederick Warne & Co. Growth is rapid, and fish may reach a weight of 0.11 kg (0.25 lb) within the first year.

Morphology

Tench have a stocky, carp-like shape and olive-green skin, darker above and almost golden below. The tail 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. Maximum size is 70 cm, though most specimens are much smaller.G. Sterba (1962). ''Freshwater Fishes of the World'' pp 249-250. Vista Books, London. A record fish caught in 2001 in England had a weight of 15 lb 3 oz (6.89 kg). The eyes are small and red-orange in colour.Females can reach weights of around 7 kg, although 4 kg is considered large. Males rarely reach over 3 kg. Sexual dimorphism is absent or 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 embedded in a thick skin, making it as slippery as an eel. Folklore has it that this slime cured any sick fish that rubbed against it, and from this belief arose the name doctor fish. Fossil - Schleie (Tinca)

Golden tench

An artificially bred variety of tench called the golden tench is a popular ornamental fish for ponds. This form varies in colour from pale gold through to dark red, and some fish have black or red spots on the flanks and fins. Though somewhat similar to the goldfish, because these fish have such small scales, their quality is rather different.

Economic significance

Tench are edible, working well in recipes that would otherwise call for carp, but are rarely eaten these days. They are shoaling fish that are popular quarries for

coarse angling In Britain and Ireland, coarse fishing (, ) refers to angling for rough fish, which are fish species traditionally considered undesirable as a food or game fish. Freshwater game fish are all salmonids — most particularly salmon, trout and ch ...

in rivers, lakes and canals. Tench, particularly golden tench, are also kept as ornamental fish in ponds as they are bottom feeders that help to keep the waterways clean and healthy.Dick Mills (2000). ''Understanding Coldwater Fish'', p 106. Interpet Publishing.

Angling

Large tench may be found in gravel pits or deep, slow-moving waters with a clayey or silty bottom and copious aquatic vegetation. The best methods and bait to catch tench are float fishing and ledgering with a swim feeder using maggots, sweetcorn, pellets, bread, and worms. Fish over 1 kg (2 lb) in weight are very strong fighters when caught on a rod.A. Lawrence Wells (date unknown). ''Observer Book of Freshwater Fishes'', pp 101-103. Frederick Warne & Co.

References

{{Authority control Fishkeeping Recreational fishing Cyprinid fish of Europe Cyprinid fish of Asia Fish of Russia Fish described in 1758 Taxa named by Carl Linnaeus Tincinae Tinca