Exposure to atrazine altered postembryonic organs development, functions and growth performance of Clarias gariepinus catfish juveniles

Atrazine is a selective pre- and post-emergence herbicide for the control of weeds. Decades after being banned, atrazine remains the most abundant pesticide in water bodies. This study evaluated the toxic effects of atrazine on the post-embryonic development of African catfish (Clarias gariepinus). Catfish juveniles of 0.89 ± 0.06 cm and with an average weight of 0.01 ± 0.005 g were exposed to five different concentrations (0, 0.03, 0.3, 3.0 and 30 μgL-1) of atrazine in three replicates. The catfish juveniles mortality were significantly increased with increasing atrazine concentrations (p<0.05). Probit analysis showed 48 hours LC50 of atrazine at 0.68   μgL-1 with 100 % mortality at 30 μgL-1. Significant reduction (p<0.05) was observed in the specific growth rate (SGR) and the relative growth rate (RGR) with increasing concentration of Atrazine treatment. Histological assessment revealed disintegration of the nervous tissues, vacuolization of the epithelium of the anterior intestine, loss of gill cytoarchitecture and distortions of the intestine in all atrazine-treatment groups. Our results show that environmentally realistic concentrations (0.30 – 30.00 μgL-1) of atrazine in the aquatic environment may adversely affect the post-embryonic development and survival of African catfish