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A 60-d feeding trial was conducted to assess the dietary protein requirement of Indian Butter catfish, Ompok bimaculatus fingerlings. Five iso-energetic semi-purified diets were formulated with varying levels of crude protein (25–45%) and fed to the experimental fish (3.29 ± 0.01 g) twice daily at satiation level in triplicate groups. Fishes were reared in indoor tanks with a stocking density of 11 fingerlings per tank. The results showed that the growth of the fish increased significantly (P <.05) with increasing protein levels upto 35% and decreased thereafter. Highest (P <.05) weight gain (247.25 ± 5.76%), carcass protein content (16.78 ± 0.04%) and protease activity (0.46 ± 0.02) coupled with lowest FCR (1.62 ± 0.04) were observed in the fish fed with 35% protein. PER and ANPR were found to decrease with increasing dietary protein levels (P <.05). Based on the second-order polynomial regression analysis of WG, it may be concluded that the dietary protein requirement of O. bimaculatus is 36.11% with a P/E ratio of 23.11 g protein MJ−1 as indicated by the maximum growth. [ABSTRACT FROM AUTHOR]

A 30-day experiment was conducted to assess the effect of tryptophan-supplemented diets on growth and survival of Pabda, Ompok bimaculatus fry. Fifty pabda fry (0.114 ± 0.02 g; 2.45 ± 0.13 cm) were stocked into each aerated aquarium following a completely randomized design consisting of four treatments with triplicate each. Four iso-proteinious purified diets were prepared with different levels of tryptophan—0%, 1%, 2%, and 3%—of the dry diet and were designated as Control, TRP1, TRP2, and TRP3 respectively. Fishes were fed with the experimental diet ad libitum four times a day. The results showed that fish fed with tryptophan-supplemented diets exhibited significantly (P < 0.05) lower cannibalism and higher survival than the control diet. Further, the tryptophan-supplemented groups showed a significantly lower coefficient of variation (%) and size heterogeneity (P < 0.05). However, the growth as measured by body weight gain, length increment, and specific growth rate of fry in tryptophan-supplemented groups was significantly lower than the control group (P < 0.05). Moreover, maximum survival (52.67 ± 1.76%) and minimum cannibalism (21.33 ± 5.70%) coupled with higher growth and performance index (0.38 ± 0.01) were recorded in the 2% tryptophan-supplemented group compared to other tryptophan-fed groups. Overall interpretation from the present study concludes that the dietary supplementation of 2% tryptophan is recommended for better survival of pabda fish, although growth was compromised. [ABSTRACT FROM AUTHOR]

The present study describes a simple, portable, and inexpensive in-pond hatchery model assembled from locally available materials for seed production of small and medium-sized carp at high efficiency. This light-weight hatchery requires minimal engineering skills for assembly and operation. Further, the hatchery water supply mechanism has built-in components to filter out sediments and zooplankton from the pond water besides maintaining the water temperature 5°C–7°C lower than the pond surface water by drawing water from a metalimnion layer without additional energy requirements. Spontaneous spawning, automatic transfer of eggs to the incubation tank, and 80% hatching rates at an egg-holding capacity of 2,000 eggs/L was recorded forBarbonymus gonionotus, Labeo bata, andLabeo rohitawith minimal human intervention. The production capacity of 0.06 million fry per cycle and estimated benefit-cost ratio of 2.48 demonstrated the high efficiency and economic feasibility of this portable hatchery. [ABSTRACT FROM PUBLISHER]