The serranids, or groupers and seabasses, are ubiquitous predators on Caribbean coral reefs and come in all shapes and sizes. Groupers are, or more accurately, were the basis of large and important fisheries throughout the region, but have become rare on fished reefs and some species are even endangered. This large and diverse family is composed of several clearly-defined subfamilies. Those subfamilies with Caribbean reef-associated representatives include the conspicuous groupers (Epinephelinae), the numerous small seabasses and hamlets (Serraninae), the deep-water basslets (Liopropominae), the soapfishes (Grammistinae), and the small reef-bass Pseudogramma gregoryi (also can be considered either a Grammistinine or a Pseudogrammatinine). There are many serranids in the region found only in deep water and not associated with coral reefs, nevertheless they are included in this section for completeness.
Larval serranids can be recognized by their relatively wide body, particularly large terminal mouth, large round eye, continuous spinous and soft dorsal fins with stout, sometimes serrated, dorsal-fin spines, and three stout spines in a short anal fin (note these characters are not all shared by the Grammistinae). Unfortunately, these characters are shared with many other percoid fishes and some serranid fin-ray counts can overlap with the abundant snappers (Lutjanidae) and grunts (Haemulidae). Within each of these families there is variation in the larval body form and meristics and often marked ontogenetic changes as well, leading to some similarity in appearance and the distinction sometimes can be difficult.
In the earlier stages, the larvae of the three families are quite similar and separation is a problem. The serranids and lutjanids even share their basic marking patterns, with melanophores on the spinous dorsal-fin membranes and on the anal fin base and caudal peduncle. A useful distinction is that serranids typically have a melanophore at the angle of the jaw and melanophores on the pectoral-fin rays, which, if present, immediately separate them from the other families. Lutjanids have a post-cleithral spine, not present in the other families, but it is not easy to see. In general, the three families have a different look as later larvae: serranids generally have large jaws with a sharp jawline (essentially a much wider gape than the others) and a particularly wide maxilla, snappers have less prominent jaw lines and an enlarging non-serrated preopercular spine, while grunts typically have smaller larvae with shorter dorsal-fin spines, and, importantly, the third anal-fin spine develops as a segmented ray in larvae and small juveniles.
Although serranid larvae share the basic features listed above, the size at settlement varies widely within the family: hamlets and basslets settle very small, from 5-10 mm SL, while some epinephelines settle particularly large, sometimes reaching up to two inches in length while still pelagic.
