Early development and growth of larval, juvenile and young Oplegnathus fasciatus reared in pond in Guangdong Province

We investigated the early development and growth of larval, juvenile and young Oplegnathus fasciatus reared in pond in Raoping, Guangdong Province. The total length of newly-hatched larvae (0 dah) was (1.875 50.060) mm with a yolk sac long in (0.7390.135) mm and short in (0.4890.089) mm. Under early rearing temperature of 22~23 ℃, the yolk was absorbed for 3-dah larvae, and only relic yolk sac could be found in 4-dah larvae, lasting only 1 d for mixotrophic period. Under conditions of 24~27 ℃, salinity 29~30 and pH 7.4~8.2, mouth opened for 3-dah larvae, but unable to forage actively; 4-dah larvae turned to exotrophic period; gill arch formed for 8-dah larvae; caudal vertebrate flexion occurred for 12-dah larvae; for 25~30-dah larvae, whose dorsal fin, pectoral, pelvic fins, anal fin and caudal fin appeared successively, and scales occurred, entered juvenile stage. For those who entered young fish stage in 40 dah, the whole body was covered by scales and bands formed, similar with adults in morphology. Correlation among total length, body length, body weight, body height in relation to daily growth could be expressed by exponent function; the ratio of body height to total length sharply decreased during 0~5 dah, after that it gradually increased and became stable after 20 dah.