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Monocrotophos (MCP) insecticides are used worldwide for protecting crops against pests. It has been reported as a pollutant that possesses long-term effects on the freshwater ecosystem. In the ecosystem, fishes are more vulnerable to aquatic pollutants as they are in direct contact with the environment. The present study was carried out to evaluate the toxic effect of MCP in freshwater fish species Channa punctatus (Bloch) under in-vitro conditions. Fish were exposed to acute dose (96 hrs LC50 = 53.996 mg/L) for 96 h of MCP. Increased SOD activity was observed at 24 hrs; however, it was significantly high in gills and kidneys at 96 hrs and in the liver at 72 hrs compared to the control. Histopathological alterations were also observed viz. fused and swollen tips of secondary lamellae, epithelial necrosis in the tissue of gills, vacuolization, congested sinusoids and disintegration of the hepatocytic cell membrane was observed in tissue of the liver and glomerular destruction, vacuolization of the inner epithelial cell was observed in the kidney at 96 hrs of MCP exposure. Overall, we observed at the median-lethal concentration (LC50) of MCP in Channa punctatus not only induce the SOD activity, but also alters the tissue histology in the vital organs of Channa punctatus. [ABSTRACT FROM AUTHOR]

For getting maximum yield intensive application of pesticides without proper disposal management has led to excess residues to flow into the neighboring aquatic ecosystems, inhabited by fish. So, the present study was conducted to assess the effects of organophosphate pesticide monocrotophos (MCP) in the level of markers in blood plasma and histopathology in air breathing fish Channa punctatus. Fishes were exposed to sublethal concentrations of the pesticide (2.7 and 5.4 mg L-1 of MCP) for a period of 30 days. Significant alterations in all the biochemical parameters were found to be dose dependent. Hyperglycemia was observed in plasma of fish after the exposure period. Increased activities of Aspartate Aminotransferase (AST), Alanine Aminotransferase (ALT), in blood plasma were found which indicated hepatic tissue damage. Total protein, albumin and albuminglobulin ratio decreased while a significant increase in creatine kinase was observed. The level of globulin increased at lower concentration of MCP while it decreased at higher concentration of MCP after 30 days. The blood serum levels of GGT (Gamma glutamyltransferase) were found decreased at all concentrations.Histopathological changes such as epithelial lifting, epithelial hyperplasia, epithelial necrosis, reduced inter lamellar space, desquamation and curling of secondary lamellae in gills; vacuolation, blood conjunctions and necrotic hepatocytes in the liver; and lamina propria, fusion of villi, and flattened villi in the kidney were observed. These structural alterations of the gills, liver, and kidney could affect respiration, osmotic and ionic regulation; absorption, storage and secretion and digestion, which in turn could adversely affect the growth and survival of freshwater fish, Channa punctatus. [ABSTRACT FROM AUTHOR]

Influence of macrophytes on freshwater snail Pila globosa was examined both in the field and in the laboratory. Study of food utilization parameters on different sized Pila globosa when provided with different set of food highlighted that small sized Pila globosa prefer same type of food as indicated by higher absorption rate when fed with Eichhornia or Vallisneria only while medium sized snail prefer different types of food as absorption rate and absorption efficiency was more for medium sized snails when they were fed with Eichhornia alternatively with Vallineria. It means that growth of medium sized snail is good when diversity of aquatic macrophytes persist. Large sized snails too prefer different types of food but due to aberration of radula, they do not rasp effectively. The aberration of radula may be caused by ageing. The nutritional value of combination food is higher than single food as observed by food conversion ratio. Smaller snails have better food conversion efficiency in comparison to larger ones. For selection of types of macrophytes, Pila globosa were first studied under natural condition. Density, biomass, growth rate and net productivity were calculated. In the month of August 2017, the density (112/m²) and biomass (1129.2 gm/m²) was maximum while nil in the winter months of November and December 2017. Growth rate (15mg/day) and net daily productivity (731 mg/m²/day) was highest at spot 1 while negative growth rate (-2mg/day) and net daily productivity (-0.41 mg/m²/day) at spot 4. [ABSTRACT FROM AUTHOR]