Tench are also sold in two colour varieties, both green and gold but they are both just colour variants of the same species (Tinca tinca).
As with many species of cyprinid fish, the natural colour variant (in this case green) occasionally throws up a gold coloured mutant which if selected will breed true. Gold tench have been farmed for several hundred years in Europe, almost certainly selected by the monks that were farming tench for food over the last millennia. The gold tench is a most attractive fish when it reaches maturity. The gold colour intensifies and the back of the fish displays a small number of contrasting intense black spots.
In the wild, tench are relatively shy fish that are predominately found in small shallow ponds. Here they happily graze in the bottom mud for small insects. They are a useful addition to a garden pond as they will happily scavenge on any uneaten food, decaying vegetation and large invertebrates. They are often described as ‘doctor fish’ as they are reputed to have slime that can eliminate parasites from other fish that rub against them. This is probably an old wives tale but it at least enhances the romantic view of this shy and beautiful fish.
Tench are one of the few cyprinids that can be readily sexed at any time of year due to the radically different shape of their pelvic fins. The males have greatly enlarged fins which look like paddles where as the female fins look very conventional.