The parrotfishes are abundant around Caribbean coral reefs, especially in beds of seagrass or macroalgae. They are typically the predominant vertebrate herbivores on and off of the reef. The taxonomy of scarids in the region is relatively simple: there are four genera, but virtually all of the species belong to two large genera Scarus and Sparisoma. The two remaining species comprise the monotypic Cryptotomus roseus and Nicholsina usta, the latter with a sibling species in the eastern Pacific.
Larval scarids share most of their basic features with their labrid relatives, such as long and continuous dorsal and anal fins with slender spines, a relatively wide caudal peduncle, stub-like pelvic fins, a pointed snout and small terminal mouth, typically light markings and no spines on the head. They can be separated from larval labrids by having a row of melanophores along or beneath the base of the anal fin, typically extending into the caudal peduncle. A number of similar-appearing families share the anal-fin row of melanophores, but have many more dorsal and anal-fin elements, usually twice as many in larval labrisomids, chaenopsids, tripterygiids, and dactyloscopids. The latter group of larvae also have narrower caudal peduncles, larger mouths, long pelvic fins, and the anal-fin row of melanophores is right at the base of the fin rays and not deep as in the parrotfishes.
The parrotfish family is remarkably uniform in many aspects and all species share the invariant fin-ray count of D-IX,10 A-III,9. Given the morphological and meristic consistency of the family, especially within the two large genera, DNA-sequence analyses are required for identifications to the species level.
Pre-transitional scarid larvae can have eyes that are a narrowed vertical oval, often markedly so. This character is shared by larval razorfishes of Xyrichtys and some larval gobies. The eye becomes fully round in larval scarids just before the onset of transitional markings.
