Rearing tench (Tinca tinca L.) larvae on live feed (Artemia) and on two transition schedules from live to dry diets

Two 60-day experiments were carried out on tench (Tinca tinca L.) from day 5 post-hatch. Density was 20 larvae L-1 and temperature 24 +/- 0.5 degrees C. In experiment 1, Artemia nauplii were the sole food, testing nauplii amounts and feeding frequency. High survival rates (between 79.5% and 95.5%) were obtained. Growth was faster as nauplii amounts were greater; the highest growth rate (11.00), weight (265.5 mg) and Fulton's coefficient (1.40) were obtained when fish were fed in excess once a day, without significant differences from the growth obtained by feeding in excess of eight times a day. In experiment 2, a dry diet for marine fish was tested as a replacement for Artemia nauplii, following two transition protocols, one faster than the other; high survival rates (between 77.7% and 87.1%) were again obtained. The slower transition allowed a growth rate of 10.14, length of 23.1 mm, weight of 158.3 mg and a Fulton's coefficient of 1.28, without significant differences from the faster transition. At all stages, growth values were significantly higher from feeding nauplii in excess as the sole food, but the required nauplii quantity was six times higher than the amount supplied to the animals fed the dry diet.