Production effect of various feeds on two size classes of juvenile tench (Tinca tinca) under the conditions of intensive rearing

The experimental rearing of tench (Tinca tinca) juveniles of two size classes with initial individual weight of 0.8 and 1.2 g was performed into flow-through aquaria connected to recirculation system during a period of 63 days. Three feeds (KARPICO Supreme 7 Ex, ASTA 2, L05/CH) with nutrient content of 37/8, 42/7 and 35/7 (% proteins/ fat) were used in the experiment. Achieved values of production indicators – feed conversion ratio (FCR) and specific growth rate (SGR) ranged from 1.84 to 4.15 and from 0.70 to 1.49 %.d–1, respectively in relationship to the size class and feed used. More favourable values were achieved with the bigger size class regardless to the diet used (FCR 1.84–3.53 and SGR 0.83–1.49 %.d–1) and the best results were achieved when using ASTA 2 feed (2.05 and 1.84 or more precisely 1.36 and 1.49%.d–1).