Tench

The tench (Tinca tinca) is a robust, thickset freshwater fish native to still and slow-flowing waters across most of Europe and western Asia. It has a distinctive smooth, slimy appearance created by very small, deeply embedded scales covered in thick mucus, along with dark olive-green to bronze coloration and small, reddish-orange eyes. A single short barbel at each corner of the mouth aids in locating food on the bottom. Tench favor heavily vegetated ponds, lakes, and slow canals, where they forage among weed beds and soft sediment. Historically nicknamed the 'doctor fish' in European folklore for its supposed healing mucus, tench remains a popular species among coarse anglers and pond keepers, valued for its hardiness and distinctive appearance.

• Thickset, slightly cylindrical body with a broad caudal peduncle and rounded fins
• Very small, deeply embedded scales covered in thick mucus, giving a smooth, slimy feel
• Dark olive-green to bronze overall coloration, occasionally golden in ornamental forms
• Small, reddish-orange eyes and a single short barbel at each corner of the mouth
• Look-alikes: young tench can superficially resemble small carp but lack the multiple barbels and large scales of common carp; golden tench is a captive-bred color variety, not a separate species

Tench are native across most of Europe and western Asia, inhabiting still or slow-moving freshwater such as weedy lakes, ponds, canals, and slow lowland rivers. They strongly favor densely vegetated habitats with soft, muddy or silty bottoms, often remaining hidden among weed beds, lily pads, or submerged debris during the day. Tench tolerate low oxygen levels and warm summer water temperatures better than many other freshwater fish, allowing them to persist in shallow, weed-choked ponds where other species struggle. The species has also been introduced outside its native range to various regions including North America and parts of the Southern Hemisphere for angling and aquaculture purposes.

Tench are primarily nocturnal or crepuscular bottom feeders, foraging mainly at dawn, dusk, and overnight for insect larvae, mollusks, crustaceans, and plant material hidden in soft sediment and weed beds, often leaving small clouds of disturbed mud as feeding signs. They are typically solitary or loosely associated rather than forming tight shoals like many other cyprinids, and tend to be secretive, remaining hidden in dense vegetation during daylight hours. Spawning takes place in late spring to summer in warm, shallow, weedy margins, where adhesive eggs are scattered among aquatic plants with no parental care. Tench are notably hardy, able to survive brief periods out of water and tolerate poor water quality, and can live for well over a decade in favorable conditions.