Life Cycle Stages and Length of Zebrafish (Danio rerio) Exposed to DDT

able up to now. The zebrafish [Danio rerio (D. rerio)] is a suitable model for full life cycle assessments because zebrafish takes only 3‐4 months to reach the sexual maturity. Moreover, they can be maintained in a laboratory environment at low cost and remain sexually active throughout the year. The test employed in this study involved exposure of zebrafish to the toxin from the fertilized egg up to the mature animal. The effect on reproduction was assessed by examination of mortality, hatching rate, body length and development of the offspring. This study encompassed the examination of two generations of fish over a period of approximately 8 months. This was regarded necessary to obtain sufficient information on the duration of each life stage and the deleterious effect of the chemical on the subsequent generation. The parameters were also investigated in the offspring of exposed parents that were subsequently reared in a toxin-free environment. The second generation was assessed up to six weeks and the difference with offspring which remained exposed to DDT was determined.