The current study was carried out to study the effect of zinc oxide (ZnO) supported on kaolinite (ZnO-K) on biological parameters, reproduction indices, semen quality, lipid profile and oxidative biomarkers for broodstock of Nile tilapia. Four tested diets were formulated; Diet 1 was control diet without addition. Diet 2, Diet 3 Diet 4 were supplemented with 30, 60 and 90 mg ZnO-K kg−1, respectively. Sixty females with average weight of 135.19 ± 3.91 g and twenty-four males with average weight of 212.51 ± 13.4 g of Nile tilapia (Oreochromis niloticus) were used. All broodstock fish were hand fed experimental diets up to apparent satiation three times daily (9:00, 12.00 and 14.00) for 4 weeks before mating. The highest hepatosomatic index (HSI %) and gonadosomatic index (GSI %) (P < 0.05) of male and female were recorded by fish fed Diet 4. The highest reproductive performance of female includes total absolute …