MORPHOLOGICAL DEVELOPMENT OF TRIPLOPHYSA BLEEKERI(SAUVAGE ET DABRY DE TH IERSANT, 1874)EMBRYO AND LARVAE

FivematureTriplophysa bleekeri, captured in themiddle section of theQ ingyijiangR iver, were selected for art-ificial fertilization in th is study1 The fertilized eggs were released into a tank (36.0× 28.0× 11.0cm3) under the watertemperature of 9.0-1218℃. Themorphological development of embryos and larvawere described and photographed with LeicaMZ16A stereom icroscope1 30 specmi enswere sampled and observed in intervals of 30m in during embryon ic stages and 12h after hatching1 The resu lts ind icated thatmature unfertilized eggswere strongly adhesive and sphericalwith prmi -rose yellow color and contained a relatively small yolk (0.94-1.10mm in diameter). The first cleavage occurred at 4h20min after fertilization1 The blastula and gastrula stages began at 19h50m in and 27h40min, respectively1 By 64h40min after fertilization, the blastoporewas found to be almost closed. Eye pigmentwas observed at 160h30min and pectoral fin buds appeared 13h50m in later. Hatching occurred at 287h and finished at 405h30min.New ly hatched larvae usually lied on the bottom of thewater, which were 4.32mm in average total length (TL) with myomeres ranging from 36 to 38 pairs.Pigment on the body and eyes appeared clearly and pectoral fin buds were well-developed1 Thick sensory buds appeared on both sides of the head and body on the 5 dph (days post hatch ing). 3 days later, the larvae reached 6.05mm in averageTL and consumed their yolk completely. In artificially reared conditions, the larvae were fed with egg vitellus and some species of Tubifex twice a day, all specmi enswere diverted into constant temperature biochem ical incubator after 21 dph. One-chamber air bladder and two-chamber ones formed on the 30 dph and 50 dph, respectively. The larvae had 52 to 53 myomereswhen the total length reached 14105mm in TL on the 55 dph, moreover, all fin rays reached the same fixed number of adult fish and 7 to 8 dark-brown speckle bands had appeared on the body sides. Yolk sac volumes of the larvae decreased at the average ratio of 0.027mm3/d. Growth in length and bodymorphometrics varied during d ifferent developmental stages1 The proportion of post-anal length to total length increased gradually from 31% at the beginning and it stabilized at about 42% finally.