Tench

The tench, known scientifically as Tinca tinca, is a freshwater fish found across Eurasia.

This species lives in environments ranging from Western Europe, including Britain and Ireland, to the Ob and Yenisei Rivers in Asia. It is also found in Lake Baikal. Tench typically inhabit slow-moving freshwater habitats. These include lowland rivers and lakes. They prefer waters with a clay or muddy substrate and plenty of vegetation.

Taxonomy is the science of naming and classifying living things. The tench was first formally described in 1758 by Carl Linnaeus. He named it Cyprinus tinca in the 10th edition of Systema Naturae. In 1764, François Alexandre Pierre de Garsault proposed the genus Tinca. While some experts once grouped them with minnows in the subfamily Leuciscinae, modern studies are different. Recent phylogenetic studies, which look at evolutionary relationships, support placing them in their own family, Tincidae. This family name was first proposed by David Starr Jordan in 1878.

The history of the Tincidae family is visible in the fossil record. These fish first appeared during the Late Oligocene period. Fossil genera like †Tarsichthys and †Palaeotinca have been identified. During the Late Miocene, species such as †Tinca furcata lived near Ohningen. Another species, †Tinca micropygoptera, lived near Steinheim am Albuch at the same time.

Other extinct species include †Tinca sayanica from Mongolia and †Tinca pliocenica from Germany. The earliest remains of the modern Tinca tinca come from the late Pliocene of the Netherlands.

Tench are remarkably hardy animals. They can tolerate low oxygen concentrations in the water. This allows them to survive in environments where even carp cannot live. They are most often found in still waters with thick plants. They generally avoid clear waters with stony bottoms. They are also completely absent from fast-flowing streams. Most tench feed at night. They look for food on the bottom of eutrophic waters, which are areas rich in nutrients. Their diet includes snails, pea clams, and animals called chironomids.

Physically, the tench has a stocky, carp-like shape. Their skin is olive-green, being darker on the top and almost golden underneath. They have small, red-orange eyes and a narrow mouth. At each corner of the mouth, there is a very small barbel. One of their most unique traits is their skin. They have very small scales that are deeply embedded in thick skin. This makes them as slippery as an eel. Because of this slime, folklore calls them "doctor fish." People once believed this slime could cure sick fish.

There is strong sexual dimorphism in tench, which means males and females look different. Females can reach weights of around 2 kg, though larger fish exist. Males rarely weigh more than 1 kg. You can recognize males by their larger, more curved pelvic fins. These fins extend beyond the anus. Males also have noticeable muscles at the base of these fins. They possess a very thick and flattened outer ray on their ventral fins. Adult females may have a more convex ventral profile than males.

Tench have significant connections to human activity. They are edible and can be used in recipes intended for carp. Many people also enjoy coarse angling for them in canals, lakes, and rivers. Large tench are known as strong fighters when caught on a rod. Some people keep them as ornamental fish in ponds. A specific variety called the golden tench is very popular. These fish can be pale gold or dark red. They may even have black or red spots. Because they are bottom feeders, they help keep pond water clean and healthy.