The Basic Research In Embryonic And Larval Development Of The Hybrid F₁by C. Idellus （♀）×E. Bambusa （♂）

The mobile hatching system was designed and tested on reservoir net cage through the combination of hatching bucket, PVC tube and oxygenation pump. About12,000fertilized eggs were obtained from a couple of silver carp Hypophthalmichthys molitrix by hormone induction and artificial propagation. The oxytocin rate and average fertilization rate were100%and (88.80±2.32)%, respectively. All of the fertilized eggs were hatched artificially in the aquatic mobile hatching system which was designed and assembled by ourselves. These eggs hatched successfully in25hours at the temperature20±25℃, and the average hatching rate was (85.26±1.93)%. It indicated that the new autonomous breeding and aquaculture model which cultivated the parent fish in net cage and hatched larva on the net cage was come true to the silver carp by reservoir net cage.In the present research, intergeneric distant hybridization between Ctenopharyngodon idellus ((?)) and Elopichthys bambusa((?)) were carried out by hormone induction and artificial propagation. The embryonic development of the hybrid F1was observed and recorded in detail, and the morphological characteristic of each development stage was also described systematically. The results showed that the average fertilization and hatching rate of the hybrid F1were (74.75±2.37)%and (43.10±3.42)%, respectively. The fertilized eggs were glittering and translucent, and were spherical in shape. The eggs had the average diameter of (4.65±0.28) mm when they were expanded by adsorption of water, and were sinking and non-adhesive. The total process of embryonic development of the hybrid F1could be divided into7stages as follows:fertilized stage, cleavage stage, blastula stage, gastrula stage, neurula stage, organogenesis stage and hatching stage. The fertilized eggs of hybrid F1hatched successfully in23hours and25minutes at the temperature of22-26℃, and the accumulative temperature during incubation was571.55℃·h.At the water temperature condition of24-28℃, the newly-hatched larva was transparent and with a mean of (4.83±0.20) mm in total length, its heartbeat and blood circulation were observed clearly. The larva turned into the later development stage since the yolk was exhausted at129h40min after hatching and was with a mean of (7.56±0.53) mm in total length. At187h35min after hatching, larva depended on exterior nutrition completely since it began to feed plankton, such as Asplanchna, and the larva started to feed artificial pellet feeds at522h25min after hatching and was with a mean of (16.45±1.25) mm in total length. Scales appeared in larvae of (22.45±5.66) mm in total length, when they were29days old. This declared that the ending of larval period. The research also discovered that during the larval development of the hybrid F1, the growth rate of larva was quite close to its male parent, and the feeding habits were similar with its female parent. Furthermore, any deadly diseases were hardly occurred in the whole cultivation process.