Abstract
The sexual pattern of a commercially important labrid fish Choerodon azurio was studied using specimens collected along the northern coast of Kyushu, Japan. Seventeen specimens collected on April 19, 1990, ranged from 164 to 315 mm in standard length. Specimens of 285 mm SL and larger were males and those smaller were females. Males were distinguishable from females by the following external appearances, i.e. squarish forehead, wider black band running obliquely on the side, reddish pectoral fin, more prominent iridescent blue spots on the latter half of the body, and deeper blue color of forehead and at the margin of caudal fin. Histological examinations of the gonads revealed that all of 6 males in the sample had secondary testes. It was concluded that Choerodon azurio is a protogynous hermaphrodite as well as many other labrid species. Although no primary males occur in the present specimens, it is necessary to study a larger number of specimens before concluding whether the species is a monandric or diandric protogynous hermaphrodite.
