TOXICITY OF THE RONSTAR TO FRESHWATER FISH CLARIAS LAZERA : A CYTOGENETIC STUDY

Abstract

This work is aimed to study different effects induced in nilotic catfish C. lazera by exposure to different doses of the herbicide ronstar as well as the protective effect of simultaneous administration (i.p.) of only one dose of ascorbic acid against different doses of ronstar intoxication. In this study, six major experiments are planned. (1) Ronstar intoxication experiments, three doses were used in these experiments; these are (2, 5.75 and 9.5 mg/L). The cytogenetic and histopathological effects of each dose are followed- up at intervals of 24, 48, 72 and 96 hrs. (2) Ascorbic acid (10 mg/kg wt.) treatment experiments; in these experiments ; the protective effect of ascorbic acid against the toxicity of each dose of ronstar are followed- up at the same previous intervals. The findings of this study are summarized as follows, a) Cytogenetic effects: Ronstar induced different types of chromosomal aberrations such as gaps, breaks and fragmentation. The most frequent type of aberrations is fragmentation. The total chromosomal aberrations are increased significantly at all applied doses compared to the control. Ronstar induced an increasing in the mitotic index at all intervals of the low dose and at 24 hrs interval for the intermediate 'and high doses. On the other hand, it decreased the mitotic index at 48,72 and 96 hrs intervals for the intermediate and high doses.