THE EFFECTS OF DIFFERENT BAITS ON THE GROWTH AND ACTIVITIES OF THE DIGESTIVE TRACT AND ENZYME OF THE LARVAE AND JUVENILE GOBIOCYPRIS RARUS

Baits is an important factor for fish growth and development. In order to find a proper bait for the larvae and juvenile Gobiocypris rarus, we divided newly hatched larvae into three groups randomly: live bait group, artificial diet group and food conversion group. Each group has three parallel samples. The fish of each group were fed since 3 dah (day after hatching) with the three different diets mentioned before, and the growth and survival rates of the larvae and juveniles were measured on 10, 15, 20, 25, 30, 35 dah. We also studied the structure and the function of the digestive tract by histological methods, and measured the digestive enzyme activities on 35 dah. Results showed that: (1) the live bait group had the highest survival rate on 35 dah; (2) from 15 dah, fish in the live bait group showed the best growing performance, and kept that trend until 35 dah; (3) muscle layer thickness and mucous cell numbers of the entire digestive tract in the live bait group were the highest, which suggested a more developed digestive tract and thus a better capacity in digestion and absorption; (4) the maximum activity of trypsase was observed in the larvae and juvenile group fed with baits. All those results mentioned above indicated that: compared with artificial diet and food conversion, live baits were the best choice for the growth and development of larvae and juvenile Gobiocypris rarus. We suggested that live baits should be taken to feed larvae and juvenile Gobiocypris rarus in the process of standardized cultivation.