Color as related to Size, Sex, and Behavior in seven Caribbean Labrid Fish Species (genera Thalassoma, Halichoeres and Hemipteronotus)

Approximately 5500 Caribbean labrid fishes belonging to seven species were caught, transported, partly on ice, to the laboratory and subsequently studied. The major portion was examined immediately; some 20 per cent were stored briefly (less than three days) at minus 20°C. Color pattern (and shape of fins) may change during adult life, varying from slightly Halichoeres poeyi) to drastically Thalassoma bifasciatum). Per species a classification into successive color phases has been introduced; these color phases are strongly related to body length. In Halichoeres maculipinna, Hemipteronotus splendens and Hemipteronotus martinicensis females are restricted to the small, first adult color phase; males have exclusively been found in the larger intermediate and terminal color phases. This confirms the prevailing opinion that labrid dichromatism represents a sexual dimorphism. In Halichoeres poeyi females are also significantly smaller than males. In the most abundant species, however, sex and color/size are not clearly related. In Thalassoma bifasciatum and Halichoeres bivittatus two types of males occur, as functional males are present in both the small, first adult color phase and in the large, terminal color phase. Functional females have been found in all sizes and colors in Halichoeres bivittatus and Halichoeres garnoti. Sex reversal from female towards male sex – a common process in all species – occurs more or less coincidental to color change. As distinct from the Sparidae, Scaridae or Serranidae the reversal proceeds via a total decline of the transforming ovary. Consequently, temporary stages of functional hermaphroditism do not occur in Labridae.