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In this study, the toxic effects on the embryos and larvae of the common carp were used as a model to investigate the synthetic pyrethroid pesticide, cypermethrin, which contaminates aquatic ecosystems. Data obtained from the cypermethrin acute toxicity tests were evaluated using the Probit Analysis Statistical Method. The control and eight test experiments were repeated five times. The number of dead embryos significantly increased in response to cypermethrin concentrations 0.0001, 0.001, 0.01, 0.1, 1, 2, 4 and 8 lg l À1 (p<0.05 for each case). The 48 h LC 50 value (with 95% confidence limits) of cypermethrin for common carp embryos was estimated at 0.909 (0.256-5.074) lg l À1 . Dose-response decreases in hatching success were recorded as 87.4, 85.0, 80.2, 71.4, 56.3, 48.6, 38.8 and 23.5%, respectively. The lowest concentration of cypermethrin (0.0001 lg l À1 ) produced a significant increase in the number of dead larvae compared to the control group (p<0.05). The number of dead larvae significantly increased with increasing cypermethrin concentrations exposed for 1-96 h (p<0.05). The highest concentration (8 lg l À1 ) showed the highest larvae mortality. The 96 h LC 50 value (with 95% confidence limits) of cypermethrin for common carp larvae was estimated at 0.809 (0.530-1.308) lg l À1 . The results of the study suggest that low levels of cypermethrin in the aquatic environment may have a significant effect on the reproduction and development of carp.

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The effect of dietary n-3 series fatty acids on the number of pleopadal egg and stage 1 juvenile in freshwater crayfish, Astacus leptodactylus was investigated. Crayfish were fed with n-3 series fatty acids supplemented diets and a control diet for 251 days. Control diet did not comprise additional n-3 series fatty acids. However, D2, D3 and D4 groups were supplemented with n-3 series fatty acids at 1%, 2% and 3% level respectively. Results showed the beneficial effects of dietary n-3 series fatty acids on the production of pleopodal egg and stage 1 juvenile number. At the end of the experiment, pleopodal egg (from 177 to 234) and stage 1 juvenile number (from 167 to 225) increased significantly with increased dietary n-3 series fatty acid level. In addition, an increase in dietary n-3 series fatty acids led to an increase in number of pleopodal egg and stage 1 juvenile produced per gram of female crayfish weight. It can be concluded that the reproductive efficiency of A. leptodactylus (i.e., pleopodal egg and stage 1 juvenile number) can be improved in controlled hatchery conditions by adding n-3 series fatty acid into the diet of this species.