MORPHOLOGICAL DEVELOPMENT AND EARLY GROWTH ON LARVAE AND JUVENILES OF HEMIBARBUS LABEO IN YAL RIVER

We studied the morphological development and early growth of larval and juvenile Hemibarbus labeo in Yal River from hatching till 43 days. The newly hatched larvae were (7.920.29) mm under the temperature of 19.625.8℃. Sensor buds were differentiated on both sides of the head 2 days after hatching (DAH) and posterior swim bladder anlage appeared on Day 3 after hatching (AH). Initial feeding appeared on Day 5 AH along with the appearance of spleen and the complete absorption of yolk sphere on Day 7 AH. The caudal tip of the notochord started to curve upward on Day 9 AH, followed by the anterior swim bladder appearance on Day 10 AH. For 14-day-old larva, the caudal folk formed and the notochord stopped curving upward. Scales were found to be appeared at the back of the operculum and all fins were well-developed on Day 32 AH that the larvae reached the juvenile stage. The entire body was covered by the scales on Day 43 AH while the fry reached the young stage. Based on morphological changes in yolk sphere, notochord, and scale, the post-embryonic development of H. labeo can be classified into 5 stages: the yolk-sac stage (06 DAH), the preflexion stage (79 DAH), the fexion stage (1014 DAH), the post flexion stage (1532 DAH), and the juvenile stage (3343 DAH). From hatching till Day 43 AH, the special growth rate of total length and body weight was 3.32% and 12.16%, respectively. The absorption of yolk sphere can be calculated through the equation: V=0.0048d3-0.0309d2-0.1240d+0.8453 (R2＝0.8933); where V =yolk-sac volume in mm3 and d = age in days. The appropriate equations for growth in the total length (LT) and body weight (W) of larval and juvenile H. labeo were as follows: LT=8.3821e0.0329d (R2=0.9586), and W=0.0048e0.0969d (R2=0.9463). In addition, the head length (LH) and body height (HB) can be calculated by the following equations: LH = -6E-05d3+0.002d2+0.1733d+0.7862 (R2=0.9577) and HB= -5E-05d3 + 0.0039d2 + 0.017d + 0.9389 (R2= 0.9621), respectively.