Effects of estradiol-17β on survival, growth performance, gonadal structure and sex ratio of the tiger puffer,Takifugu rubripes (Temminck & Schlegel, 1850), fingerlings

Abstract

Systematic research was performed to assess the survival, growth performance, gonadal structure and sex ratio during and after sex reversal induced by estradiol-17β in tiger puffers. The fish of 20 days after hatching (dah) were immersed in different doses (0.2, 2, 20, 100 ppb) for 60 days. There were significant differences in survival rates among groups (p < .05). With the increase in the estradiol-17β dose, the survival rates of tiger puffers decreased, revealing a linear regression relationship with log10 (estradiol + 1; p < .05). The growth tendency of fish in the low-dose group was similar to those in the control group over the same period. The growth in the 20 ppb dose group was significantly slower than in the low-dose and control groups in fish of same age (p < .05), but was significantly faster than in the 100 ppb dose group (p < .05) after 60 days. Intersex fish were categorized into intersex I, II and III types, according to the feminization degree from low to high. Phenotypic intersex puffer fish were found in the 2, 20 and 100 ppb dose groups. Intersex ratios in 2, 20 and 100 ppb were 10%, 43.3% and 46.7%, respectively, the ratios except the ones in 2 ppb group being significantly higher than those in the control group (p < .05). Moreover, 100.0% male induction for intersex II and III types occurred in 20 and 100 ppb groups. Together, these results indicated that estradiol-17β at a dose of 20 ppb was most effective for pseudo-female production.