Masculinization in common carp (Cyprinus carpio) by androgen immersion: The interaction effect of hormone concentration and immersion time.

Synthetic androgens (male hormones) administered to fish nursery are being used in aquaculture to avoid sexual differentiation and unwanted spawning at the eggs or the first feeding fry stage of fish. Present trial was conducted with the aim to produce male common carp (Cyprinus carpio) by egg immersion technique. Through this little insight, the effect of different hormone concentrations (17α-methyltestosterone @ HC:150, 300, 450 and 600 µgl-1) with immersion times (IT: 24, 48 and 72 hrs) and their interaction effect (HC x IT) on the hatching percentage of Cyprinus carpio eggs, percent survival and percent of male's production was evaluated specifically. Results showed that egg hatching percentage decreased with increased IT likewise, survival of treated fry was affected by increasing the IT (P<0.001). The main interaction effect of HC x IT showed that the highest percent of male individuals (95%) was obtained at 450-600 µgl-1 HC for 72 hrs IT, followed by 88-92.50% at 150-300 µgl-1 HC for 72-hrsof IT, 87.50% at 48-hrs of IT for rest of the hormone treatments, and lowest 47.50% was recorded in control (P<0.05). Increased percent male of Cyprinus carpio was obtained with increasing HC across all ITs. It was observed that the immersion treatment at 600µgl-1 for 72 hours was more effective to change the sex ratio of pre hatch Cyprinus carpio. A comparative outlook made from this experimental trial that sex induction of Cyprinus carpio by eggs immersion using synthetic male steroid hormone is an alternative safe technique of fish sex reversal in contrast to oral administration of hormone in fish feed.