Frying affects the nutritional quality of fish detrimentally. In this study, using Catla catla and mustard oil, experiments were carried out in varying temperatures (140–240 °C), times (5–20 min), and oil amounts (25–100 ml/kg of fish) which established drastic reduction of 44.97% and 99.40% for polyunsaturated fatty acid (PUFA)/saturated fatty acids (SFA) and index of atherogenicity (IA) profile, respectively. Artificial neural network (ANN) was implemented successfully to provide an association between the independent inputs with dependent outputs (values of R² were 0.99 and 0.98; RMSE were 0.038 and 0.046; and performance were 0.038 and 0.067 for PUFA/SFA and IA, respectively) by exhaustive search of various algorithms and activation functions available in literature. ANN model–based meta-heuristic, stochastic optimization formalisms, genetic algorithm (GA) and particle swarm optimization (PSO), were applied to optimize the combination of cooking parameters for improving the nutritional quality of food which improved the nutritional value by maximizing the PUFA/SFA profile up to 63.05% and minimizing the IA profile to 99.64%. Multi-objective genetic algorithm (MOGA) was also employed to tune the inputs by maintaining a balance between the contrasting outputs and enhance the overall food value simultaneously with multi-objective (beneficial for health, economic, and environment-friendly) proposal. MOGA was able to improve the PUFA/SFA profile up to 44.76% and reduce the IA profile to 92.94% concurrently with the reduction of wastage of culinary media and energy consumption, following the optimized cooking condition (118.92 °C, 6.06 min, 40 ml oil/kg of fish).

The current research was designed to investigate the adverse effects of dense ores in different organs exposed to these metals polluted water on three edible fish species (Wallago attu, Catla catla and Tilapia nilotica), sampled from River Sutlej at Head Islam (Hasilpur), Pakistan. The assimilation of different elements Ni, Fe, Cd, Cr and Pb in body parts of normal fish took from the fish farm and also made a comparison among understudied fishes. Overall absorption of ores in fishes was ranked as Fe > Ni > Cr > Cd > Pb. A remarkable variation in the deposition of elements in different organs of three fish species and was analyzed statistically (p < 0.05). High levels of ore assimilation in fish organs pointed out potential health risks for the fish, other aquatic organisms and human beings too.

The present study assessed the impact of fingerling stocking of Indian major carps (Gibelion catla, Labeo rohita, and Cirrhinus mrigala) on fish yield in 24 small reservoirs of Central India. The time series data on fish stocking and yield were collected from the State Fisheries Department, Govt. of Chhattisgarh, for the year 2008 to 2016. The fish yield increased significantly (p < 0.05) from 87.11 to 379.13 kg/ha/year due to stocking indicating significant impact on fish production. The relationships between area, stocking density, and fish yield of reservoirs were also assessed. Stocking had a significant positive impact on fish yield (t test, p < 0.05). The important water quality parameters were also studied to have a conspicuous picture of eco-hydrological characteristics of these selected small reservoirs. The study forms a baseline for the small tropical reservoir fisheries of Central India (Chhattisgarh state) and suggests regional strategies for sustainable fisheries enhancement and management, employment generation, and nutritional security of a large number of fish-eating population.

Water pollution is gradually increasing in natural waters through anthropogenic activities. This study aimed to use fish scales as a bio-indicator of pollution, along with water quality parameters, and the assessment and detection of selected heavy metals in water samples collected from the River Chenab, including the Chakbandi drain that gathers domestic sewage waste and industrial effluents from Faisalabad and deposits it into this freshwater body. All water quality parameters (pH, total dissolved solids (TDS), total suspended solids (TSS), salinity, conductivity, biochemical oxygen demand (BOD), chemical oxygen demand (COD), phenols and sulphates) and concentrations of selected heavy metals (Cd, Cu, Mn, Pb and Cr) were found to be considerably higher than permissible limits as defined by the WHO, and therefore capable of causing ill health effects in aquatic organisms. Specimens of fish scales from selected fish were described qualitatively and observed quantitatively. In Catla catla, Labeo rohita and Cirrhinus mrigala, the scales showed several deformities in shape and different scale structures such as circuli, radii and annuli. In each of the three types of fish, considerable variation in the morphology of their scales was observed in specimens collected from polluted sites.

The current study was conducted to assess the hematological and histopathological changes in major carp (Catla catla) exposed to different concentrations of copper (Cu) and cadmium (Cd). For this purpose, Catla catla fish, weighing approximately 230–235 g, were randomly divided into four groups and then exposed to acute doses of Cu (1.25 ppm), Cd (4.5 ppm), and their mixture (2.25 ppm) for 96 h and then 20, 30, and 40% respectively for a period of 30 days. Results showed that red blood cells (RBCs), hemoglobin (Hb), hematocrit (Hct), lymphocyte, and monocyte decreased significantly, while the total white blood cell count and neutrophil population significantly increased in experimental groups as compared with the control one. Histopathological examination of liver tissues showed karyorrhexis, hepatic cells degeneration, congestion, and hemorrhages. Microscopic analysis of gills’ sections revealed lamellar atrophy, telangiectasia, and necrosis of lamellar epithelial cells. In the kidneys, different histopathological ailments like atrophy of glomeruli, necrosis of renal tubular cells, increased urinary spaces, degeneration of renal tubules, and melanomacrophage aggregates were observed, while in the intestine, atrophy of villi, sloughing of epithelial villi, and congestion were seen after 30 days of exposure. In conclusion, the study indicates that exposure to Cu and Cd for longer period of time causes adverse hematological and histopathological changes in Catla catla fish.

Presence of formaldehyde as a preservative in commonly available fishes (Labeo rohita, Catla catla, Anabas testudineus and Clarias gariepinus) has become a serious health concern in the public health of eastern region of India. Formaldehyde content was determined using high-performance liquid chromatography (HPLC). Results showed high formaldehyde content in frozen carp (19.66 and 23.3 mg/kg in Labeo rohita and Catla catla, respectively); however, the amount of formaldehyde was significantly reduced in boiled and fried fish (80 °C and 100 °C for 5 min) in mustard, coconut, and sesame oils. However, formaldehyde contents in non-carp fishes (Anabas testudineus and Clarias gariepinus) were almost negligible, compared to those in L. rohita and C. catla. In vivo toxicity studies showed a time-dependent increase in blood formaldehyde levels in rats after they were fed formaldehyde-contaminated fish (23.3 mg/kg) for 7 days. Histopathological analysis of the stomach of rats fed contaminated fish showed destruction and granulation of the protective mucus layer and detachment from the secretory layer. Taken together, our results indicated that continuous consumption of formaldehyde-contaminated carps commonly available in the eastern region of India may be associated with adverse health effects.

Concentrations of heavy metals (Cu, Ni, Zn, Cd and Pb) were measured in sediments, water and liver and kidney tissues of three Indian major carps (Labeo rohita, Catla catla and Cirrhinus cirrhosus), belonging to two different weight groups (250 and 500 g), collected from ponds at two different sites (Nalban bheri and Diamond Harbour). The tissues were analysed for the levels of different antioxidant defence systems such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GRd), glutathione S-transferase (GST), glutathione (GSH) and malondialdehyde (MDA). Concentrations of all the metals were significantly higher (P < 0.05) in sediment, water and the tissues from Nalban bheri compared to those in Diamond Harbour. Metal concentrations were the lowest in C. cirrhosus, which increased with an increase in fish weight, and the liver accumulated higher amount of metals than the kidney. Activities of all enzymatic and non-enzymatic antioxidant parameters except GPx and GRd were significantly higher (P < 0.05) in the tissues from Nalban bheri than those in Diamond Harbour. Significant multicollinearity was found in the values of SOD, CAT, GST, GRd, GPx and MDA with Pb, Cu and Ni in all three fish species at Nalban and with Cd in L. rohita and C. catla. Principal component analysis results revealed that stress response in a polluted site was directly regulated by an amalgamation of GSH profile and the levels of MDA in a synchronized manner. The study indicated a tissue-specific and species-specific difference for heavy metal-induced oxidative stress response in fish and a correlation between different heavy metals and individual oxidative stress markers.