What Divers Should Know About Tench

Drifting through the calm, verdant depths of a freshwater lake or a slow-moving lowland river, you might glimpse a robust, olive-green form blending seamlessly with the aquatic plants. This is the tench, a fascinating resident often found in still waters with abundant vegetation and a muddy or clay substrate. With its distinctive stocky, carp-like shape, darker back fading to an almost golden underside, and small, red-orange eyes, it's a creature perfectly adapted to its preferred murky environment, even tolerating waters with low oxygen where other fish struggle.

Though generally nocturnal feeders, primarily seeking out small bottom-dwelling animals and snails, you could still spot these shy fish during a day dive. Look closely for a very small barbel at each corner of its rather narrow mouth, a subtle detail that sets it apart. While these fascinating fish can grow up to 70 cm (28 inches), most specimens encountered underwater will be much smaller. Their thick, slimy skin, embedded with very small scales, earned them the old nickname "doctor fish" due to folklore, adding another intriguing layer to an encounter with this freshwater native.