UTTAR PRADESH JOURNAL OF ZOOLOGY

Poisonous plants are traditionally used for fishing in several parts of North-East India; however, their toxicological effects on aquatic organisms require systematic evaluation. Derris taiwaniana is used locally as an ichthyotoxic plant and is also reported in traditional medicinal practices. The present study assessed the acute toxicity and genotoxic potential of the aqueous seed extract of Derris taiwaniana (AEDT) in adult zebrafish (Danio rerio). Adult zebrafish were exposed to different concentrations of AEDT under a 96 h semi-static exposure system, and mortality was recorded at 24, 48, 72 and 96 h to estimate lethal concentration values. Genotoxicity was evaluated using the micronucleus assay in peripheral blood erythrocytes after 96 h of exposure to selected AEDT concentrations. AEDT exposure produced concentration- and time-dependent mortality in adult zebrafish. The calculated LC50 values were 3.662 mg/L at 24 h, 2.792 mg/L at 48 h, 2.448 mg/L at 72 h and 2.214 mg/L at 96 h. Exposed fish also showed behavioural signs of distress, including opercular hyperventilation, erratic swimming, surface gasping, loss of equilibrium and sinking before death. In the micronucleus assay, AEDT caused a dose-dependent increase in micronucleated erythrocytes compared with the negative control. The highest tested AEDT concentration, 2.4 mg/L, produced a micronucleus frequency of 6.52 ± 0.47%, while the negative control showed 0.47 ± 0.08%. These findings indicate that the aqueous seed extract of D. taiwaniana has acute toxic and genotoxic effects in adult zebrafish under the experimental conditions used. Further studies are required to identify the active toxic constituents and clarify the mechanisms involved.