The tench encapsulates everything good about coarse fish - obliging but challenging; strong when hooked but hardy and long lived; and endowed with a robust yet delicate beauty. The olive green back and pale, sometimes yellow, belly accentuate the colour of its small orange-red eyes, and the large, rounded fins give obvious indications of its fighting ability. Golden tench are an ornamental variety, orange/yellow in colour, with dark blotches over their bodies.
Our forbears assumed - incorrectly - that the thick layer of slime which covers tench had prophylactic or curative properties for other fish which rubbed against a tench's skin, hence the misnomer 'doctor fish'. This protective mucus layer is characteristic of fish inhabiting slow-moving rivers and stillwater fisheries.
Telling the difference
Unlike most fish, it is quite easy to tell the tench sexes apart, the key external feature being the shape of the paired pelvic (hindmost) fins - in males, they are broad and hand-shaped, whereas females have slimmer, spear-shaped pelvics. Females also grow somewhat larger than males, notwithstanding that their weight can be enhanced considerably by spawn which is not shed until water temperatures approach about 20° C.
Small tench are something of an enigma. Even where they are known to be present in large numbers, they often remain uncaught until they grow to ½lb or so, probably because of their dietary requirements and their habit of residing in dense beds of water plants. Larger fish are primarily bottom feeders, consuming worms, water-snails, insect larvae and crustaceans, as well as water plant material. Their well-known bubbling activity is probably a consequence of the fish rooting around in the mud, and then expelling trapped gasses via their gill rakers.
Boom for biggies
There is no doubt that tench have grown larger in recent years. The most likely explanation is that the fish have benefited from the extra natural food that has developed as agricultural fertilisers have entered and enriched many fisheries. Certainly, l0lb+ fish - which used to be deemed figments of anglers' vivid imaginations - are now caught each year.
If you are interested in cheap tench fishing tackle and bait, please click here.