| Morphological development and feed changeover of the larvae, juveniles and young fish of Epinephelus coioides ♀ x
E.lanceolatus♂ were observed and studied within a month since hatching. The fertilized eggs were hatched in water with temperature 30~ 33℃, salinity 30.0, pH8.1 and DO≥5.0 mg/L, and the larvae were hatched after 18~20 hours and started to eat protozoa after 65~67 hours when they were hatched. In the beginning, the larvae with weak swimming ability and micro-mouth only feeding small plankton such as ball algae and rotifers. The second dorsal and ventral spines appearing when the larvae were 7~8 days old, and the ratio of these spines to total-length reached the maximum (close to 0.5) when the fish were 14~18 days old. At the 20th day, the ratio decreased obviously with elongation of other spines. After 29 days of hatching, most fish's back or whole body were covered with scale，and the individual differences of fish larvae was significant. In this study, the larvae main were fed with rotifers and other protozoa in the first 13 days after the larvae hatched, yet a small part of copepods larvae began feeding at the 10th day, their main feed changed into the
copepods and cladocerans after 13 days. |
