Tench (Tinca tinca)

Photo of a juvenile Tench by Viridiflavus

By Terry White

Comments

The tench, I believe, is much underrated as a pond fish as it's best points are not automatically obvious. The wonderful vivid green and golden colouring is generally not seen when viewed from above, not being gregarious or growing as large as carp it also tends to stay in the deep and mid-water parts of the pond so can be difficult to spot. Not surface feeding as a rule (Although I have know tench to take floating pellets) it often loses out to carp, orfe and goldfish.

It's also over sold in reference to being a "pond cleaner" a dubious selling point of most bottom feeding fish as they will root around in the debris looking for insect larva and other food particles but they will also produce waste and not remove or eat silt as is normally implied.

It was also believed that the mucus on tench could heal other fish that had parasites or other diseases and help treat a wounded fish. This led to the tench often being called a Dr Fish, as far as I know there is no proof to backup those claims.

By nature tench seem to prefer a silty environments with plenty of aquatic vegetation, they are pretty hardy and can tolerate quite low oxygen levels. They do best in mid summer when the water temperatures are between 20-26°C.

Tench can do very well in most ponds of over 1000 gallons (4500ltrs) but are best in normal garden ponds or as an unobtrusive insect predator in wildlife ponds. They coexist well with other pond fish and with other tench; they will often form small shoals if a number of them are kept together.

Description

The tench is a predominately bottom feeding cyprinid (Soft-finned mainly freshwater fishes) that prefers slow flowing and still waters. They can be found in some rivers, waterways, ponds, canals, lakes, grave pits and reservoirs throughout their native range from Western Europe (UK & Ireland) to central Asia (Lake Baikal), they have also been introduced into many countries including Australia (1876). The tench can tolerate salt and can also be found in the lower brackish stretches of rivers.

A stocky deep rounded muscular body and rounded in the fins, face and mouth, which is narrow and has a small barbel at either end. The body scales are very small and deep set into the skin, the mucus covering is quite heavy giving the fish a smooth slippery feel when held. The upper body is normally a dark olive green to brown colour but it can vary from almost black to a light golden green. The underside is a light golden brownish orange. The gill plates and cheeks are bright iridescent green and the fins a translucent grey colour, the caudal fin is barely forked and looks squarish and the dorsal fin is set back on the body and rounded, the eyes are small and golden orange with a black centre.

A golden tench is available as an ornamental fish and varies from a golden yellow to orange in colour normally with some dark spotting in places.

A tench can live in excess of 30 years, weight in at 5.5kg (14 lbs) and can reach 70cm in length (27.5 inches) but most will be much smaller even at full maturity.

At around two years of age the male pelvic fins are much larger than the females, the pectoral and anal fins can also be larger. Reaching maturity at around 3 years for males and 4 years for females.

Spawning usually takes place during the summer with water temperatures between 18-20°c. The females produce around 125,000 eggs per kilo of body weight; the small (0.8-1.4mm) adhesive eggs are deposited in shallow water generally onto aquatic plants and roots. Spawning can take place in batches with fortnightly intervals between each batch. The eggs hatch after 4-6 days the young tench are 4-5mm long and will attach themselves to water plants initially.

The tench fry feed mainly on plankton, small insect larvae and micro-crustaceans. Small tench feed mostly on crustaceans and micro-crustaceans, insect lava, and small chironomids and larger tench on aquatic insects, worms some molluscs and crustaceans.