No abstract

Fish meal (FM) has excellent protein and lipid profile. However, FM is losing its acceptability and substituted with plant protein due to FM has high price, high demand, and sustainability issues in global aquaculture production. In this study, experimental diets were prepared by substituting FM with fermented soybean meal (FSM) or normal and untreated soybean meal (SM) to assess the effects on growth, hematology, innate immunity, gut physiology, and digestive enzyme activities in juvenile silver barb, Barbonymus gonionotus. Five diets, that is, 40% FM (FM 40), 20% FM + 20% FSM (FM 20 + FSM 20), 20% FM + 20% SM (FM 20 + SM 20), 40% FSM (FSM 40), and 40% SM (SM 40) were fed to the fish two times daily for 90 days. After 90 days of feeding trial, FM 40, FM 20 + FSM 20, and FM 20 + SM 20 diet groups showed significantly higher weight gain (WG) and specific growth rate (SGR) compared to the FSM 40 and SM 40 diets. Hepatosomatic index (HSI) and viscerosomatic index (VSI) were significantly higher in fish fed with the FSM 40 and SM 40 diets than those of fish fed with the FM 40 diet. Hematocrit, hemoglobin, and erythrocyte count were significantly lower in fish fed with the SM 40 diet compared to fish fed with the FM 40 and FM 20 + FSM 20 diets. Superoxide dismutase and catalase activities in the liver were significantly higher in fish fed with the SM 40 diet compared to fish fed with the FM 40 diet. However, serum thiobarbituric acid reactive substances in fish fed with the experimental diets were unaltered. Fish showed significant reduction of villus height (Vh) in the anterior and posterior intestine of fish fed with the FSM 40 and SM 40 diets, whereas muscular thickness was opposite to the findings of Vh. Digestive enzyme activities in intestine were significantly higher in fish fed with the FM 40 diet compared to those in the SM 40 diet. The results of the present study revealed that the 50% of FM can be replaced by FSM or SM as a source of protein without affecting the growth of juvenile silver barb.

Background: Freshwater fish in Bangladesh are adversely affected by the washed off pesticides, used in agriculture. The aim of this study was to evaluate the impacts of a commonly used organophosphate pesticide on freshwater stinging catfish, Heteropneustes fossilis, which envisioned that the possible threats might occur by this organophosphate group to other species in the wild. Methodology: To study the potential hazards of Envoy 50 SC on H. fossilis, fry of the fish were exposed to the acute toxicity tests. Changes in the hematological parameters, organ-specific histomorphologies, and brain acetylcholinesterase (AChE) activities were determined by treating the fish with agricultural recommended dose and below that dose of 0.015 and 0.0075 ppm, respectively. Results: LC 50 of Envoy 50 SC for the fish was determined as 0.151 (0.014-0.198) ppm. Pesticide abruptly altered the normal tissue structures of the gill, liver, and kidney. The major alterations included were the gill lamellae missing, gill clubbing, hyperplasia, nuclear hypertrophy, vacuolation, glomerular expansion, increasing diameter of the renal tubules, hemorrhage, necrosis, and pyknosis. In blood cells, changes observed in the peripheral nuclear erythrocyte were large lymphocyte, dead cell, fusion of the cells, binucleated cells, tear-shaped cells, ghost cells, senile cells, and abnormal structures of the cells. Significantly lower (P < 0.05) red blood cell (RBC) count and AChE activities in fish brain due to the pesticide exposure suggested the reasons of abrupt behavior, increased oxygen consumption, and fish mortality at higher concentration of this organophosphate pesticide. Conclusion: The presence of pesticides, even at low concentrations, caused deleterious effects on the earlier life stages of a comparatively harder and robust fish, suggesting a wider range effect on the more sensitive wild life, in particular decrease in survival in their native environment. Therefore, measures should be taken to minimize the risk of contamination of the aquatic environment by such toxic chemicals.

Increasing demand, uncertain availability, and increasing cost for fishmeal (FM), fish nutritionists have been driven to find alternative sources of protein. The aim of this study was to evaluate the effects of substituting FM with soybean meal (SM) on growth performance of silver barb, Barbonymus gonionotus. Five diets were prepared 0%SM (100%FM), 25%SM (75%FM), 50%SM (50%FM), 75%SM (25%FM) and 100%SM (0%FM) by replacing FM with SM. B. gonionotus having initial length and weight of 8.62±0.9 cm and 8.80±3.11 gm were fed each diet twice a day for 45 days. Fish sampling was done fortnightly. Significantly higher (P<0.01 and P<0.05) weight and length gain were found up to 75%SM compared to 100%SM. The specific growth rate (6.01±0.34%d-1) was significantly higher (P<0.05) in 50%SM compare to 75%SM and 100%SM. Considering the result of present study we recommend to replace 50% SM as a source of protein with 50% FM for better growth of B. gonionotus. Asian J. Med. Biol. Res. June 2020, 6(2): 149-154