What they look like
Tench have a stocky, carp-like shape, dark green on the back and greenish brown to dark brown on the sides and almost golden below. The body coloration may vary with habitat, ranging from almost black in shallow, muddy lakes to much lighter in running water or clear water lakes. The caudal fin is square in shape. The other fins are distinctly rounded in shape. Tench fins are dark gray to dark brown to black. The mouth is rather narrow and provided at each corner with a very small barbel. They have small distinct red-orange eyes. Adult females have a more convex ventral profile when compared with males. Males may also possess a very thick and flattened outer ray to the ventral fins.The tench has very small scales, which are deeply imbedded 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. An ornamental variety of the tench is called the golden tench and is a popular ornamental fish for ponds. This form varies in color from pale gold through to red, and some fish have black or red spots on the flanks and fins.Back to Top
Where they live
Tench thrive best in enclosed, preserved waters, with a clayey or muddy bottom and with abundant vegetation. This species is rare in clear waters across stony ground, and is absent altogether from fast-flowing streams. During summer months, the tench seeks cooler temperatures by concentrating in deep holes and shaded areas. It tends to be inactive during the day, resting in favored habitats such as dense aquatic vegetation, and forages for food after dusk.
The tench is tolerant of low levels of dissolved oxygen, and are reported that the species can survived in waters with a low oxygen level that would quickly kill other fishes. The Tench is a remarkably hardy fish. Historical accounts from England claim fishmongers would bring individuals to market and return the unsold fish back into water to live (presumably until their next trip to market. Live tench have also reportedly been shipped during winter in boxes of weeds. Individuals from northern Europe can withstand temperatures near freezing and have been reported that the species burrows into the mud during winter for protection against the cold where it remains in a motionless condition similar to hibernation. The species is also reported to be tolerant to low levels of salinity.
The tench was originally imported into North America from Germany by the U.S. Fish Commission in 1877 and distributed to at least 36 states by 1896. Subsequent stocks probably had other origins. For example, at least one other introduced stock was imported from Italy. Intentional stocking and accidental escapes have increased its distribution in the U.S. The tench has been reported in at least 39 states, but most introductions were unsuccessful, and the species has maintained reproducing populations in only a few areas. In Washington State the tench is considered an aquatic nuisance.Back to Top
What they eat
Tench feed mostly at night on algae and invertebrates of various kinds that they root up from the bottom, including snails. The diet of small tench (2-5 inches) consisted of aquatic insect larvae, and small flies. In winter, it stays in the mud without feeding itself.Back to Top
Tench typically get up to about 18” long and 10-12 pounds. It is reported that individuals reach sizes of 31 ½ inches in length and weighing over 13 pounds. Wild tench may live up to 11 years.Back to Top
Males generally mature in their third year, a year before female. Spawning occurs around summer when water temperatures reach around 65 °F. The species aggregates for spawning in shallow, densely vegetated areas where the adhesive eggs are broadcast over vegetation. The Tench is a batch and will spawn over artificial substrates resembling vegetation. The species is reported to reproduce readily in artificial habitats, for example, in some reservoirs in California. The female can lay over 500,000 eggs depending on her size. The eggs are small, yellow or green, and hatch in 3-8 days at 72-75 °F. After hatching the larvae remain attached to the plants for several days. Growth is rapid, and fish may reach a weight of 0.25 pounds within the first year.Back to Top
6 lbs. 4.32 oz. caught in Sprague Lake, Adams/Lincoln County by angler George J. Schmidt on June 8, 2004