Male morphological characteristics and mating success in a protogynous coral reef fish, Halichoeres melanurus

Morphological sexual differences and their effects on male mating success w ere investigated in the tailspot wrasse, Halichoeres melanurus, on a subtro pical coral reef of Okinawa, southern Japan. Male mating territories were e stablished along the reef edge from late April to early October, during whi ch time pair-spawning occurred just before sunset in the male territories. Territorial males were larger and brighter than females in this protogynous fish. The males had longer, colorful ventral fins and colorful caudal fins , both of which were used during courtship. Multiple regression analysis of the effects of male characteristics on male mating success revealed that t he yellow spot at the pectoral fin base was the most effective. It is sugge sted that large body size is favored in male-male competition for establish ing mating territories and that conspicuous body color is favored in female mate choice.