Abstract:Morphological and quantitative characteristics of Verasper variegatus in early life stages including embryonic development, yolk sac larva, pre-flexion larva, post-flexion larva, and juveniles were recorded. The eggs are 1.75mm 0.08mm in diameter, without oil globule and spherical in shape when they are suspended in sea water. There is negative a relationship between the temperature and the hatching time, and the calculated lower threshold temperature for hatching of embryos is 5.14 ℃. The larvae hatched out 159h post fertilization at temperatures of 11±0.5 ℃, salinity of 31-32, and DO≥5mg/L. The newly hatched larvae is transparent and 4.95±0.15mm in total length. Larval development and growth completely depended on the energy from the yolk sac and oil globe till 7 DAH (days after hatching). Meantime, mouth and anus opened, larvae entered the mixed feeding stage. Larvae entered the complete exogenous feeding stage after the yolk was completely absorbed at 11DAH. The first feeding food was L type rotifers Brachionus plicatilis. Larvae began to feed rotifers at 7 DAH. At 11 DAH, larvae were fed nauplii of brine shrimp Artemia salina at densities of 0.5 1.5 ind./ml till 46 DAH. Weaning to commercial diet started at 31 DAH and larvae fed mainly commercial diet after 40 DAH. There is no swim bladder present all through the early life history. The flexion of notochord started at 17 DAH at a total length of 7.32 0.23 mm (n=30), and finished at 33DAH when the total length reached 11.2 0.33 mm (n=30). Meanwhile, metamorphosis began at 33 DAH and completed at 50 DAH with the left eye moved completely to the right side, and the juveniles entered the bottom life stage. At 70 DAH, lateral line formed and the juveniles entered the young stage with the total length up to 25.3 3.23 mm (n=30), with similar appearance as the adults. The dorsal fin, pectoral fin, pelvic fin, caudal fin, and anal fin reached their full numbers at 70DAH. There were 4-5 black spots on the dorsal and pectoral fins at 45DAH, which is same as the adults.
