No abstract

No abstract

No abstract

Toxicity tests reveal that the zebrafish (Brachydanio rerio) is very sensitive to malathion, an organophosphorus insecticide, and 24 to 96‐h LC50 values showed a gradual decrease as the exposure time was increased. Zebrafish exposed to long‐term sublethal concentrations failed to spawn and invariably exhibited skeletal deformities. Possible causes of the reduced gonadosomatic index and skeletal deformities are discussed.

Abstract. In the present research, both male and female zebrafish, Danio rerio (Hamilton), were exposed to 96-h LC5 values of Deltamethrin (0.016 µg dm -3 ) and Achook (0.025 µg dm -3 ) for three months. The fish were then returned to normal water and allowed to breed to permit observations of fecundity and hatchability. The results show significant reductions in fecundity and hatchability in comparison to the control group. Fecundity was reduced by 54.12% in the fish treated with Deltamethrin and by 17.81% in those treated with Achook. Significant decreases in hatchability of up to 49.7% were noted in the Deltamethrin group and of 36.9% in the Achook treated fish. The number of unhatched/dead eggs increased significantly (P < 0.05 for each case). It was concluded that low concentrations (96-h LC5 values) of both pesticides can have a significant impact on the reproduction of zebrafish.