In the present in vivo study, we provide a comparison of toxicological consequences induced by four different types of spherical nanoparticles (NPs)-silver nanoparticles (AgNPs, 40 ± 6 nm), nickel (NiNPs, 43 ± 6 nm), cobalt oxide (Co₃O₄NPs, 60 ± 6 nm), and chromium oxide (Cr₃O₄NPs, 50 ± 5 nm)-on freshwater fish . Fish were exposed to NPs (25 mg/L) for 21 days. We observed a NPs type-dependent toxicity in fish. An altered behavior showing signs of stress and a substantial reduction in total leukocyte count was noticed in all NP-treated groups. A low total erythrocyte count in all NP-treated fish except for Co₃O₄NPs was discerned while a low survival rate in the case of Cr₃O₄NP-treated fish was observed. A significant decrease in growth and hemoglobin were noticed in NiNP- and Cr₃O₄NP-treated fish. A considerable total protein elevation was detected in NiNP-, Co₃O₄NP-, and Cr₃O₄NP-treated groups. An upgrading in albumin level was witnessed in Co₃O₄NP- and Cr₃O₄NP-treated groups while a high level of globulin was noted in NiNP- and Co₃O₄NP-exposed groups. In all NP-treated groups, a depleted activity of antioxidative enzymes and pathological lesions in liver and kidney were noticed.