The present study was undertaken to generate first time information on the optimal stocking density for fry to fingerling rearing of Hypselobarbus pulchellus. Rearing was carried out for 90 days at stocking densities of 15, 30, 45, 60, 75, 90, 105 and 120 fish/m2 in 24 m2 cement tanks. While the length of fish at harvest ranged from 3.42 cm in 120/m2 to 6.11 cm in 15/m2 densities, the weight ranged from 0.41 g in 120/m2 to 2.62 g in 15/m2. The final length and weight were inversely related to the stocking density. However, no significant variation (p > 0.05) in length was observed among the stocking densities of 15, 30, 45 and 60/m2. Similarly, the final weight of the fingerlings also did not differ (p > 0.05) between the stocking densities 15, 30 and 45/m2. Further, increase in stocking densities resulted in significant reduction in final length and weight, with the highest stocking density of 120/m2 recording the lowest values. The condition factor varied between 0.95 and 1.17 with no difference (p > 0.05) among the stocking densities. The survival of fingerlings at harvest ranged between 81 and 90%, but was not statistically different. The growth in terms of length and weight of H. pulchellus was superior under stocking densities 15, 30 and 45 fish/m2 compared to higher densities. Hence, the stocking density of 45 fish /m2 is recommended as the optimum for fry to fingerling rearing of H. pulchellus.

A growth trial was conducted for 60 days in 4 × 4 m outdoor cement tanks with soil base to evaluate growth, feed conversion efficiency, carcass composition and digestive enzyme activity of rohu, Labeo rohita, fed diets incorporated with guar meal replacing fish meal. The isonitrogenous and isocaloric diets used were—a fish meal based diet (Control) and diets with fish meal replaced at 30%, 60% and 90% levels with guar meal. The growth parameters, feed conversion and protein efficiency ratio, survival and condition factors did not differ significantly among the different treatments. While the activity of the digestive enzymes in the hepatopancreas did not differ (p > 0.05) among the treatments, the activity of digestive enzymes estimated in the intestine showed reduction at higher levels of guar incorporation. Carcass composition analysis revealed the highest moisture and lowest crude protein, fat and gross energy levels in fish from 90% replacement group. Lowest moisture and highest crude protein, fat and energy levels were observed in fish from 30% replacement. The study indicated the possible use of processed guar meal as a fish meal substitute in the diet of rohu, resulting a reduction in feed cost without compromising on fish growth and quality.

A study was conducted with non‐conventional ingredients to test their efficacy as fishmeal (FM) replacers in the diet of fringe‐ lipped carp. Labeo fimbriatus first feeding larvae and fry were reared for 30 and 60 days in indoor, 50 L, aerated, circular plastic tanks at 100 and 30 numbers tank−1, respectively. In the first feeding larvae to fry rearing experiment (Exp. 1), the fish were fed with either of the following isonitrogenous and isocaloric diets – live plankton, FM diet, green bottle fly (Lucilia sericata) larvae meal (GBFLM) diet and silkworm pupa (SWP) diet. The fry to fingerling rearing (Exp. 2), was also conducted using the same diets described above except live plankton. All compounded diets were formulated to contain 40% crude protein for the experiment 1 and 35% for experiment 2 and were fed ad libitum. Triplicate tanks were maintained for each treatment in both the experiments. In Exp. 1, the mean final weight of fry was higher with plankton and FM diets, while no difference (p > .05) was observed between FM and GBFLM diets. Weight of fish fed SWP diets was not statistically different from those fed GBFLM diet. No difference (p > .05) in final length, survival and condition factor was recorded. Analysis of digestive enzyme activity of whole fish revealed lower (p < .05) activity of amylase in fish fed plankton. In Exp. 2, no difference (p > .05) was observed between the different diet groups in terms of mean final weight, length, survival and condition factor. Analysis of digestive enzyme activity of whole fish revealed no difference (p > .05) in the activity of digestive enzymes between the treatments except a lower (p < .05) activity of trypsin in FM diet and lipase in FM and GBFLM diets. Since the survival and condition factors of animals is the most important aspect during nursery rearing, similar (p > .05) values recorded in different treatments indicate the possibility of incorporation of these non‐conventional protein sources in the diet of L. fimbriatus during first feeding larvae to fry and fry to fingerling rearing.