Effect of Stocking Density on the Growth and Survival Rate of Magur (Clarias
batrachus) Fry in Laboratory and Nursery Ponds
An attempt was made to determine the effect of stocking densities on the growth of Magur (Clarias batrachus) fry (5.1 ± 0.10 mg) for a period of 28 days in trays in laboratory. Clarias batrachus fry were stocked at the rate of 30, 40, 50 and 60 fry/tray i.e. 3, 4, 5 and 6 fry/litre of water. Stocking density of 30, 40, 50 and 60 fry/trays were designated as treatment I, II, III and IV respectively the fry was feed by grounded tubifex. The survival rate of C batrachus fry upto 28 days were found 92.3, 90.3, 89.3 and 80.1% at the stocking density of 30, 40, 50 and 60 fry/tray, respectively. The treatment had no significant effects on the ADG, SGR and weekly growth increment in length. Average daily gain of Clarias batrachus was found 20.80, 21.80, 19.46, 19.31 in treatment I, II, III and IV. The value of SGR (%) was 17.58, 18.68, 17.33 and 17.30% in the above treatments. The final cumulative gain in length were 39.50 ± 0.51, 39.90 ± 0.10, 38.60 ± 0.60 and 37.60 ± 1.20 (mm) and fry reached to 588.3 ± 33.29, 604.3 ± 16.01, 550.0 ± 25.00, 546.6 ± 28.00 mg over a period of 28 days in treatment I, II, III and IV, respectively. The second experiment was performed to determine the effects of two selected feeds on the growth and survival rate C. batrachus fry in different nursery ponds for a period of 28 days. The protein level of the supplemental diet was 32.24% in feed I and 27.75% in feed II which were designated as treatment I and II. The feed was supplied daily at the rate of 10% of the body weight of the stocked C. batrachus fry. C. batrachus having an average initial length of 3.86 ± 0.05 cm reached to the final length of 7.26 ± 0.05, 7.12 ± 0.02 and in the gain in body weight and 3.38 ± 0.02 g under feeding treatment I and II, respectively. Analysis of variance (ANOVA) indicated that a significant difference (p>0.05) was observed in case of ADG, SGR, survival rate, cumulative growth increment in length and weight.
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