Nanoparticles such as Fe, FeO, CuO, Zn, ZnO, and Se play an important role in aquaculture. These compounds are essential minerals to increase fish growth and supplemen-tation in feeds because practical feedstuffs contain low levels of these microminerals. Dietary supplementation of nanoparticles produces greater survival, growth, antioxidant levels and immunity of aquatic organisms including fishes. The present study deals with the impact of different quantity of green synthesized iron oxide nanoparticles on growth, enzymatic, biochemical changes, and hematology of Zebrafish Danio rerio. Anisomeles malabarica leaf extract was used for the synthesis of iron oxide nano-particles and characterized by XRD, SEM, EDAX, and FT-IR. Six feeds were prepared with different quantity of synthesized iron oxide nanoparticles (F1 - Control, F2 -10 mg, F3 – 20mg, F4 – 30mg and F5 – 50mg) and feed ingredients are fish meal, groundnut oilcake, wheat flour, and tapioca flour. Growth, digestive enzymes (protease, amylase, and lipase), biochemical constituents (total protein, carbohydrate and lipid) and hematological parameters were estimated after 30 days. ‘t’ test and One-way ANOVA was used for the analysis. The feed consumption, feed conversion efficiency, weight gain, percentage growth, relative growth rate, assimilation, metabolism, gross and net growth efficiency were higher in F5 containing 40mg of green synthesized iron oxide nanoparticles (1.98 ± 0.29, 0.19 ± 0.02, 0.85 ± 0.32, 2.88 ± 0.74, 2.21 ± 0.70, 1.61 ± 0.11, 44.31 ± 10.58 and 42.11 ± 9.46). 40mg of iron oxide nanoparticles supplemented feed enhanced the digestive enzymes and biochemical constituents of Zebrafish. The results conclude that 40 mg iron oxide nanoparticles supplemented feed enhanced the growth, digestive enzymes, biochemical constituents, and hematology of Zebrafish.