author(s)
Anagha T, Subodh Gupta, Prem Prakash Srivastava, Narottam Prasad Sahu, Rajendran KV, Tincy Varghese, Thongam Ibemcha Chanu, Munish Kumar and SR Krupesha Sharma

abstract
The present study was aimed to examine the toxicological effect of two sub-lethal doses of titanium dioxide nanoparticle (TiO2 NPs) injection on Labeo rohita. 1/50th and 1/10 th of 96 hour LD₅₀ were selected as the lower and higher sub-lethal doses respectively. The exposure was for 21 days. At the end of the experiment, fishes were collected randomly, blood samples were collected, and then fishes were dissected out to collect ovary and liver. The enzymatic antioxidant activity of superoxide dismutase (SOD) and catalase (CAT) were estimated from homogenates of ovary and liver. Serum biomarkers such as cholesterol and triglycerides (TAG) were also found out. The 96hr LD₅₀ value estimated was 528.3±0.002µg Kg^-1. The two -sub-lethal doses selected for exposure were 10.6 (lower) and 52.8 (higher) µg Kg^-1 of TiO₂ NPs. Among the serum biomarkers, cholesterol showed a non-significant increase and TAG did not show any significant difference from the control. Hepatic SOD and CAT activities were significantly elevated with concentrations of TiO₂ NPs. No significant differences were noticed in the ovarian SOD activity. Histopathological architecture did not alter with titanium dioxide nanoparticle injection.