Differences in sex reversion and growth between normal and neomale stock in half-smooth tongue sole, Cynoglossus semilaevis

The present study evaluated the difference in the sex ratio (the genotypic and phenotypic female ratios) and the growth parameters between normal male offspring and neomale offspring under tank culture conditions. The phenotypic female ratio of normal male offspring (20.46-63.79 %) in four families and three stocks was remarkably higher than that of neomale offspring (5.21-10.53 %) in three neomale families and three neomale stocks (p < 0.01), while there was no significant difference between normal male offspring (30.41-70.60 %) and neomale offspring (29.7-70.83 %) in the genotypic female ratio (p > 0.05). The sex reversion ratio (SRR) was analyzed based on the genotypic and phenotypic female ratios. In neomale offspring, the SRR ranged from 84.25 to 92.53 %, while in normal offspring the SRR ranged from 9.65 to 34.60 %. There was a significant difference between normal male offspring and neomale offspring in the SRR (p < 0.01). The weight and length were measured at the ages of 300, 600, and 720 days. The growth rate was analyzed by the statistics, and there was a significant higher growth rate in the normal family than the neomale family (p < 0.05). The results suggest that the slower growth in the neomale offspring is responsible for the high SRR.