Thick and heavy, the tench has an olive green or darker back with bronze coloring on its belly. It also comes in an orange shade and is sometimes stocked in artificial ponds or aquariums. Its scales are small, as are its eyes, and it’s described as being excessively slimy.
Habitat and diet
Tench prefer shallow lakes, rivers, and backwaters with a great deal of vegetation. In some parts of the world, they spend the winter buried in mud.
To find food, the tench uses short sensory organs that protrude from each side of its mouth, called barbels, to search the river or lake bottom for snails, mosquito larvae, and other small creatures. Tench also eat detritus, algae, and plant matter.
Male tench reach maturity at around two to three years old, females about a year later. That happens in late spring or summer when the female releases her eggs every 15 days or so until the temperature cools. She does this near plants so that the sticky eggs attach to the vegetation. One or two males will swim by and release sperm. Once the eggs hatch, the larvae stay attached to the plants for several days before swimming off.
In Europe, tench are threatened by the alteration of waterways and other kinds of river engineering.