Chlorpyrifos (CPF) is a widely used organophosphate pesticide which has an unfavorable impact on the aquatic ecosystem. This work was designed to compute the LC50 and lethal concentration (96-hr) of chlorpyrifos for Labeo rohita. The LC50 and lethal concentration (96-hr) of chlorpyrifos for Labeo rohita was determined as 10.39±0.03 and 15.31±0.05 µgL-1, respectively. During acute toxicity test, behavioral changes in Labeo rohita were also observed i.e. rapid opercular movement, profuse mucus secretions, imbalance swimming, increased surface activity, loss of equilibrium, convulsion, body discoloration, and decreased hyperactivity. Jumping of fish out of exposed medium proved the avoidance behavior against pesticide toxicity.

An experiment to assess the changes in hematology, serum biochemistry and DNA integrity in Cirrhinus mrigala exposed to metals was conducted. Results showed that the copper exposure to the fish had more pronounced effects as it resulted in significantly lower RBCs, Hb, Hct and higher WBCs, while Zn exposure showed least toxic effect towards hematological parameters as compared to other metals. Among all the exposure durations of metals, the 96-hr exposure caused maximum negative effects on fish. Lower level of serum Na, Cl, Alb and TP were observed in fish under the exposure of Cu as compared to other metals while K, AST and ALT levels were higher. However, least toxic effect on all above-mentioned parameters were noticed in Zn exposed fish. It is also observed that the highest DNA damage in terms of percent genomic DNA template stability (%GTS) was observed in Cu exposed fish while the Zn exposure to fish resulted in lowest DNA damage. The results revealed maximum squared Euclidean distance between Cu treated fish and the control. This study proposed that the occurrence of toxic metals in aquatic environment has strong impact on hematology, serum biochemistry and DNA integrity of fish.

Plant proteins are considered most suitable to replace fish meal because they are cheap, readily available, and abundant. However, plant proteins are not digested efficiently in fish due to the presence of complex protein structures. Therefore, this preliminary study was conducted to evaluate the effect of bromelain-fermented plant diets on the digestive enzyme activities and muscle proximate composition of Labeo rohita. For this purpose, healthy fingerlings with an average initial weight of 10±0.2 g were procured and acclimatized under laboratory conditions. Then, 20 fingerlings were transferred to each of 20 glass aquaria (160 L capacity) in three replicates. Five diets were prepared using plant meals and were fermented using 10, 20, 30 and 40% bromelain powder for 48 hours at 55°C. The control diet was not fermented. Fermented diets were fed to fish for 90 days, and then digestive enzyme activities and muscle proximatecomposition were determined. Fish fed bromelain-fermented diets (10-40%) showed a significant increase in digestive enzyme activities (protease and lipase) compared with the control group. However, no significant effect was observed on the amylase activities in fish fed bromelain-fermented diets. Muscle proximate composition revealed that crude protein (CP) contents were increased while crude fat (CF) contents were decreased in fish fed fermented diets compared with the control group. However, no significant differences were observed in moisture and ash contents. In conclusion, fish fed fermented diets showed enhanced activities of digestive enzymes (protease and lipase) and crude protein contents in the muscle of L. rohita. Therefore, it is recommended to conduct a detailed trial on bromelain fermentation.

Plant proteins are considered most suitable to replace fish meal because they are cheap, readily available, and abundant. However, plant proteins are not digested efficiently in fish due to the presence of complex protein structures. Therefore, this preliminary study was conducted to evaluate the effect of bromelain-fermented plant diets on the digestive enzyme activities and muscle proximate composition of Labeo rohita. For this purpose, healthy fingerlings with an average initial weight of 10±0.2 g were procured and acclimatized under laboratory conditions. Then, 20 fingerlings were transferred to each of 20 glass aquaria (160 L capacity) in three replicates. Five diets were prepared using plant meals and were fermented using 10, 20, 30 and 40% bromelain powder for 48 hours at 55°C. The control diet was not fermented. Fermented diets were fed to fish for 90 days, and then digestive enzyme activities and muscle proximatecomposition were determined. Fish fed bromelain-fermented diets (10-40%) showed a significant increase in digestive enzyme activities (protease and lipase) compared with the control group. However, no significant effect was observed on the amylase activities in fish fed bromelain-fermented diets. Muscle proximate composition revealed that crude protein (CP) contents were increased while crude fat (CF) contents were decreased in fish fed fermented diets compared with the control group. However, no significant differences were observed in moisture and ash contents. In conclusion, fish fed fermented diets showed enhanced activities of digestive enzymes (protease and lipase) and crude protein contents in the muscle of L. rohita. Therefore, it is recommended to conduct a detailed trial on bromelain fermentation.