THE EMBRYONIC DEVELOPMENT AND FINGERLING CULTURE OF LOACH, PARAMISGURNUS DABRYANUS SAUVAGE

The large-scale loach, Paramisgurnus dabryanus Sauvage, is a cobitoid fish distributed mainly in waters along the middle and lower Changjiang (Yangtse) valley. It was introduced recently to South China as one of the species for pond polyculture.The embryonic development of this fish is divided into 52 stages, which are consecutively illustrated by drawings in the present paper. Video tape records were also made during the course of investigation.Comparing with the development of the related species, Misgurnus anguillicaudatus, the embryonic development of this fish shows several specific characteristics, i.e. blood circulation appearing earlier, 2—3 melanophores located at the base of the pectoral fin but no vascular networks, and the emergence of barbels and of the pelvic fin bud being retarded for two development stages.The incubation period lasts about 36 hours at 28—31℃. The range of the optimal water temperature for the growth of fingerlings is 24—35℃. 50 day-old individuals reach an average weight of 2.5 g and then can be removed to larger ponds for commercial rearing. The suitable stocking density in ponds is one juvenile per 5 litres of water, and the body-weight of fish at the end of rearing is nearly seven times larger than those cultivated in the aquaria with a density of 6—10 fish per litre. The natural food, such as zooplankton, aquatic insects, etc. gave best result for growth. As to the artificial feeds, press residues of peanut proved better than rice bran.