LAUSR

The Serranidae are well known for protogynous sex change. The red-belted anthias Pseudanthias rubrizonatus inhabits Kagoshima Bay. We aimed to estimate the body size and age of P. rubrizonatus exhibiting sex change. We determined their sex based on the body color and the observation of their gonad. The sampled fish were 0–7 years old, although no individuals 1 or 6 years old were found. The fork length (FL) ranged from 10 to 114 mm. According to estimates from growth curves calculated from the body size of fish of each sex, the theoretical size of individuals exhibiting sex change was 96.9 mm FL and 14.1 g body weight. Gonadal transitions were observed in fish of 81–100 mm FL, 7–14 g body weight, and 2–3 years old, regardless of their apparent sex. These gonads included atretic oocytes in the testis. Most males had ovarian cavities in the testis. Histological observation showed that P. rubrizonatus is a protogynous fish species.