Tench

The tench or doctor fish (Tinca tinca) is a fresh- and brackish-water fish of the order Cypriniformes found throughout Eurasia from Western Europe including Britain and Ireland east into Asia as far as the Ob and Yenisei Rivers. It is also found in Lake Baikal. It normally inhabits slow-moving freshwater habitats, particularly lakes and lowland rivers.

Habitat

The tench is most often found in still waters with a clay or muddy substrate and abundant vegetation. 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 cannot survive.

Tench feed mostly at night with a preference for animals, such as chironomids, 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. Growth is rapid, and fish may reach a weight of 0.11 kg (0.25 lb) within the first year.