The widespread use of silver nanoparticles (AgNPs) results in the unintentional release into the water body. Therefore, understanding of the potentially harmful impacts of AgNPs and Ag‐salt on aquatic animals is a need of time. This study was design to analyze the oxidative stress and histopathological damages in Cyprinus carpio. The synthesis of AgNPs from Halymenia porphyraeformis and by reduction of chemical was done. Nanoparticles were characterized with UV–Visible spectroscopy, SEM, XRD, and FTIR analysis. The comparative toxicological effect of chemically synthesized silver nanoparticles (Ch‐AgNPs), green silver nanoparticles (Gr‐AgNPs), and Ag‐salt on C. carpio was analyzed. For oxidative stress analysis, different tests Lipid peroxidation (LPO), catalase, glutathione reduction (GST), and glutathione S‐transferase (GST) were performed. The highest LPO 245.168 ± 0.034 was recorded in Ch‐AgNPs‐treated gills and the lowest 56.4532 ± 0.02 was found in Gr‐AgNPs‐treated liver. Maximum GSH 56.4065 ± 0.13 was observed in Gr‐AgNPs liver and minimum 40.781 ± 0.54 was recorded in Ag‐salt gills. The maximum quantity of catalase 68.0162 ± 0.09 was noted in the Ag‐salt‐treated liver and the minimum was calculated 17.3665 ± 0.01 in the liver of Ch‐AgNPs and highest values of GST 765.829 ± 0.11 were recorded in gills of Gr‐AgNPs and lowest 633.08 ± 0.26 in the liver of Ch‐AgNPs‐treated fish. In conclusion, maximum destruction was found in the gills and liver of the fish treated with chemical and green AgNPs followed by Ag‐salt as compared to control. The adverse effects of AgNPs and Ag‐salt were probably related to the oxidative stress in the fish that lead to histopathological damage of its vital organs.

Nanoparticles in aquatic bodies cause serious harm to the aquatic organisms when accumulated in high amounts. However, green nanoparticles synthesized using plants can be less toxic as compared to chemical nanoparticles. Hence, we designed our study to investigate the toxicological effects of chemical and green zinc oxide nanoparticles (ZnO NPs) on the biological activity of juvenile Cyprinus carpio. The green ZnO NPs were synthesized from Solieria robusta, and chemical ZnO NPs were synthesized using zinc chloride solution and ammonium hydroxide. Characterization was done by using light microscopy, scanning electron microscope (SEM), Fourier transmission infrared radiation, and X-ray diffraction (XRD) techniques. The highest absorbance of nanoparticles was observed at 360 which confirmed the synthesis of ZnO. The SEM analysis showed that green nanoparticles were hexagonal while the chemical nanoparticles were spherical to cubic in shape. Definite peaks were observed in XRD of green and chemical NPs at 2θ angles 45.84 and 32.18 , respectively. Oxidative stress was determined by chemical analysis of catalase, glutathione S-transferase (GST), glutathione (GSH), and lipid peroxidation (LPO) activities. The toxicological effects of chemical ZnO NPs on the catalase, LPO, GST, and GSH activities were more than green ZnO NPs. The histopathological investigation proved that the effect of chemical nanoparticles was worse than green ZnO NPs. More tissue damage was found in chemical nanoparticles than green synthesized nanoparticles. It was concluded that chemical nanoparticles can be replaced by green nanoparticles, as green nanoparticles are eco-friendly with less toxicological effects. This replacement can limit the toxic effect of nanoparticles when they get accumulated in high amounts in water bodies.