Tench

• Its tiny, almost invisible scales give it a characteristically smooth, slimy look.
• It eats insect larvae and molluscs, supplemented with plant matter from the bottom.
• It lives in well-vegetated lakes, ponds and slow-flowing rivers of Europe and Asia.
• It is among the European fish most resistant to lack of oxygen and to warm, stagnant water, and it survives where other cyprinids cannot cope.
• It buries itself in the mud for the winter and spends months almost inactive, without feeding.
• Its skin is covered in a very thick mucus. Hence the medieval legend of the doctor fish: other fish were believed to rub against it to heal their wounds, and its slime was even held to work as a human remedy. There is no basis whatsoever for it.
• It has tiny scales set deep in the skin, which give it a smooth feel unusual in a cyprinid.
• In Spain the tench has deep culinary roots in Extremadura and Castilla y León, with traditional pond farms.

Skeleton type

Vertebrate - internal bony skeleton (fish)

Habitat and environment

Lakes, ponds and slow-flowing rivers with plenty of vegetation across much of Europe and Asia

Birth weight

Larva 4-5 mm long on hatching

Size at birth

4-5 mm long at hatching

Sexual maturity

3-4 years (the male before the female)

Gestation / incubation

3-6 days of incubation at 20 °C

Litter / clutch size

23,000 to 380,000 eggs per female, in several batches 14 days apart

Life expectancy in captivity

A documented record of over 30 years in captivity

Sources consulted: Academia.edu; Pond Life; ResearchGate; USGS NAS; Irish Specimen Fish Committee; MDB Fish Fact Sheet; FishBase; Farnham Angling Society