Embryonic and postembryonic development of Polyodon spathula

Polyodon spathula parents cultivated in a pond in Fujian were stimulated to spawn followed by artificial fertilization using the dry method.The embryonic and postembryonic development observed indicated that(a) the mature eggs were rich in yolk and oval in shape with an average size of(2.41±0.04) mm×(2.30±0.03) mm;(b) the cleavage pattern was special radial holoblastic;(c) at water temperature of 17.0 ℃to19.8 ℃,the embryonic development lasted from 115.75 h to 147.0 h,with a hatching time of 134.75 h;(d) the postembryonic development consisted of three stages,i.e.,yolk-sac larva,late-stage larva and juvenile;(e) at the water temperature of(20±0.5) ℃,the 8-day-old larvae had their yolks exhausted,and the larvae began to feed and entered the late-stage larva;(f) the larvae entered into juvenile stage at water temperature of(22±0.5) ℃ on the 10th day;and(g) when the water temperature reached 21 ℃ to 23 ℃,the 35-day-old fingerlings had an average length of(74.9±16.12) mm,body weight of(2.32±0.55) g and length of snout almost 30% of its eventual length,and the body proportion was similar to the adult paddlefish.