Tench - Morphology

Morphology

Tench have a stocky, carp-like shape, olive-green skin, darker above and almost golden below. The caudal fin is square in shape. The other fins are distinctly rounded in shape. The mouth is rather narrow and provided at each corner with a very small barbel. Maximum size is 70 cm, though most specimens are very much smaller. The eyes are small and red-orange in colour. Sexual dimorphism is weak, limited to the adult females having a more convex ventral profile when compared with males. Males may also possess a very thick and flattened outer ray to the ventral fins. Males are generally smaller than females but can be recognised by having more curved lower fins and noticeable muscles around the base of the fins generally absent in female.

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.