Family: CHAETODONTIDAE, Butterflyfishes
FAMILY CHAETODONTIDAE
BUTTERFLYFISHES
Chaetodontids have deep, strongly compressed bodies, small extendible mouths at the end of an elongated snout of varying length; bands of small brush-like teeth on jaw; no strong spine on preopercle; 1 continuous dorsal fin, VI-XVI stout spines, membranes between the front spines are deeply indented, no notch between the spiny and soft portions; anal fin III-V stout spines; tail fin varies from rounded to slightly concave; scales rough, covering head, body, and median fins; a large "axillary process" scale at the upper base of the pelvic fins.
Most butterflyfishes live in water shallower than 20 m, but some are restricted to deeper areas, down to at least 200 m. Butterflyfishes, which are often strikingly colored, have delicate shapes, swim gracefully, and are active during daylight. Many species feed on live coral polyps, while are omnivores with a mixed diet of small benthic invertebrates and algae; a few feed in midwater on zooplankton. Young butterflyfishes are highly prized as aquarium fishes. Chaetodontids have a distinctive late postlarval stage called a tholichthys which has large bony plates on the head and front body.
The family is worldwide and contains 14 genera and 132 species, which occur mainly in tropical seas around coral reefs. Only four species (three endemics and one Indo-Pacific) from four different genera are known to regularly occur in the tropical eastern Pacific.
