MASS REARING OF COREGONUS SP. LARVAE USING 17-α-METHYLTESTOSTERONE AS THE GROWTH STIMULATOR

摘要

Mass tank-cage rearing of Coregonus sp. larvae was carried out using 17-α--methyltestosterone (MT) as the growth stimulator. The experiment was divided into three phases and lasted for 103 days. In tank rearing (days 1-20) the fish were fed artificial starter feeds exclusively. In phase I of cage rearing (days 21-61) the fish were placed in illuminated lake cages where they consumed natural food (zooplankton) only. In phase II of cage rearing (days 62-103) artificial feeds were also used. Starter and fry feeds contained 6 ppm MT in the experimental group, and no MT in the control one. Average hody weight and length (l.t.) at the end of each phase were (respectively in the experimental and the control group): 32.2 and 28.4 mg, 18,8 and 17.6 mm (tankrearing); 356 and 355 mg, 36.3 and 36.9 mm (cage rearing phase I), 1311 and 1165 mg, 58.3 and 55.5 mm (cage rearing phase II). Fish survival during the whole experiment was 57.4 % in the experimental group and 51.4 % in the control one.