Many parrotfishes (Scaridae) co-occur in mixed-species aggregations as juve
niles, but diverge in resource use and social structure as adults. Focal ob
servations of 3 juvenile parrotfishes (Scarus coeruleus, Sparisoma aurofren
atum, Sparisoma viride) were conducted on inshore patch reefs in the Florid
a Keys to examine feeding rates, food type, habitat use, and aggressive int
eractions. All species overlapped extensively in their use of space and foo
d. Home ranges physically overlapped, and the proportion of microhabitats p
resent within home ranges was similar for all species. Home range size incr
eased with body size for S. coeruleus and S, aurofrenatum. Diets of all spe
cies were extremely similar. All fed selectively from the available foods a
nd fed primarily (>50% total bites) on the calcareous macroalga Halimeda op
untia despite its potentially high energetic costs of procurement. low food
value. and predicted avoidance. Focal individuals interacted aggressively
with conspecifics, other juvenile parrotfishes, damselfishes, and occasiona
lly grunts and wrasses. S. aurofrenatum and S, viride were most aggressive
toward conspecifics. Aggressive interactions with adult parrotfishes were r
are. Both Sparisoma spp, were chased more often by damselfishes than any ot
her species. These findings support the growing body of evidence that herbi
vorous fish do not feed randomly from all potential foods. The aggressive i
nteractions observed among juvenile parrotfishes are likely affecting their
use of resources and may act as a precursor to subsequent territoriality a
s adults.