Eggs of the silver carp (Hypophthalmichthys molitrix) absorb water after release from the female, causing them to become turgid and increase substantially in size. Prior observations have suggested that silver carp eggs may swell and burst in soft waters. Identifying water hardness threshold values is needed for the successful incubation of silver carp (H. molitrix) eggs.Aim of the work
The present experiments were designed to determine the effect of water quality on the reproductive performance of the silver carp.Material and methods
In this study, we tested the effect of water hardness from three sources – tap, El-Serw Fish Farm, and Lake Manzalah – on silver carp egg enlargement and hatching success.Results
Water chemistry variables, including temperature, dissolved oxygen, and pH, were consistent among tests. The observed results, during induction of spawning, indicated that the application of human chorionic gonadotropin, at a dose of 1500 IU/kg, was effective for inducing the final stages of maturation, ovulation, and spawning in silver carp in ripe spawners. Water hardness during egg hardening had a significant effect on the hatching success of eggs originating from the same parent fish. Hatching success rates were highest for eggs hardened in the hardest water treatment (132 mg/l) and lowest for eggs hardened in the softest water treatment (45 mg/l). Both embryonic and larval development have been described, and there was no difference in the tested waters.Conclusion
Our research suggests that water hardness of 45–132 mg/l is suitable for the reproduction of silver carp.