INDUCED SPAWNING AND LARVAL REARING OF CAPTIVE YELLOWFIN PORGY, ACANTHOPAGRUS-LATUS (HOUTTUYN)

Females of yellowfin porgy (Acanthopagrus latus) were induced to spawn by a single injection of 1000 IU kg(-1) human chorionic gonadotropin (hCG), 0.5 ml kg(-1) Ovaprim (sGnRH-A in combination with domperidone) or a combination of hCG (500 IU kg(-1)) with Ovaprim (0.25 ml kg(-1)) . Ovaprim, at a dosage of 0.5 ml kg(-1), was the most effective. Fish injected with propylene glycol or 500 IU kg(-1) body weight of hCG did not spawn at all, Fertilization rates ranged from 72 to 84% and hatch ing rates were between 60 and 88%. The hatched larvae were reared in 3 0-45 t cement tanks and fed initially on trochophore oyster larvae (Cr assostrea gigas), followed by rotifers (Brachionus plicatilis), Artemi a nauplii, copepods and finally weaned onto a zein micro-coated diet, Metamorphosis started when larvae reached 9.7 mm TL at 30 days of age, and was complete by Day 38 when larvae were 12.4 mm TL. From Day 20 a fter hatching, the larger larvae (>7 mm TL) began to exhibit agonistic behavior. Intestinal swelling was frequently observed in larvae at 22 -25 days after hatching (5-8 mm TL). Two types of skeletal malformatio ns, lordosis (10-21%) and brachyospondyliosis (1-4%), were frequently observed in the juvenile stage. Initial larval stocking densities were inversely correlated with survival(r = -0.80, P < 0.01), Optimal init ial stocking density was 10-15 larvae l(-1). Larval rearing trials for growth and survival to 50--56 days produced juveniles of 20 mm averag e total length, at a survival rate ranging from 0.7 to 27.5%.