The Spawning, Growth, and General Behavior of the Bluehead Wrasse, Thalassoma Bifasciatum (Pisces: Labridae)

Aspects of the life history of the tropical marine fish Thalassoma bifasciatum were investigated on a reef in the Florida Keys during a two-year period. Emphasis was placed on analyses of both spawning and growth.

Two types of spawning patterns, aggregate and paired, were observed; in both, the eggs and milt were expelled in midwater. Size-frequency analyses of ovum-size indicate peaks of spawning activities on Florida reefs at intervals of 1½ to 2 months throughout the year, with individuals spawning many times during the year.

Average maximum standard lengths of 55 to 65 mm are attained in about a year, with exceptional individuals reaching 90 mm or more. Size-frequencies of standard lengths indicate that peaks of abundance of particular sizes are related to sex, although no difference in growth rate between adult males and females could be demonstrated.

Other aspects discussed are coloration, morphometry, foods and feeding, general behavior, and mimics. A synonymy is included.