The objective of the present study was to determine the length (mm) for sex transformation of hermaphroditism in white spot grouper Epinephelus coeruleopunctatus as a basis for developing breeding technology. Fish sampling was carried out between April and October 2013 in Padang City waters, Indonesia. A total of 56 white spot groupers were recorded during the study; of these 22 were male, 28 female and 6 samples were not recognized regarding sex preference. Sex differentiation was detected at a length of 183 mm, and at this size the fish are female. Sex transformation to male begun to occur at 302 mm total length.