Family Chaetodontidae
Members of the Family Chaetodontidae (i.e., butterflyfishes) typically are oval-shaped, deep-bodied and highly compressed.  Chaetodontids have a single, continuous dorsal fin and a scaly axillary process at the upper base of the pelvic fins.  Many chaetodontids are brightly coloured and thus popular aquarium fishes.  Most species have a dark vertical bar across the head that obscures the eye and a dark "false eye" on the posterior portion of the body.  The combination of the eyebar and false eye confuses potential predators about the identity and/or orientation of the fish (Neudecker 1989).

Butterflyfishes are probably most similar in appearance to angelfishes (family Pomacanthidae), but can easily be distinguished from them.  Butterflyfishes lack the distinctive spine(s) at the angle of the preopercle in angelfishes.  Also, angelfishes lack the scaly axillary process at the base of the pectoral fins and false-eye spots.

Chaetodon lunula

The lateral line is complete with < 60 scales.  The pectoral fins are rounded, not elongated.  The snout is only slightly pronounced and the head profile is steep.  Dorsal fin XI-XIII (22-25), anal fin III (17-19).  Pectoral rays 15 or 16.

Most chaetodontids are identified by their distinctive colour patterns (see photo above).  The body is primarily yellow with some brownish markings.  The vertical ocular bar is black; posterior to the ocular bar is a broad, white bar.  These two bars together give the appearance of a raccoon's mask.  Large black and brown markings occur on the upper dorsum posterior to the white bar and dorsally to the base of the dorsal fin.  There is a black blotch at the caudal peduncle.  The dorsal, caudal and anal fins are edged in black.  Juveniles have a black blotch at the posterior base of the caudal fin.

Chaetodon fasciatus (Red Sea raccoon butterflyfish) is a similar species from the Red Sea. In Florida, a similar species is the reef butterflyfish (Chaetodon sedentarius), which lacks white markings on head and wide dark wedge on rear dorsal and body.

Summarised from Pyle (2001); Allen et al. (2003), Randall (2005); illustrated in Burgess and Axelrod (1973); Myers (1999).

Like many reef fishes, butterflyfishes spawn their pelagic eggs into the water column where they are fertilized and dispersed by the currents (Hourigan 1989).  Eggs are small (<1 mm) and embryos hatch about 30 hours after fertilization (Leis 1989).  The larvae subsequently spend about 40 days in the plankton before settling to the reef (Hourigan and Reese 1987).  Age estimates for the duration of the pelagic phase (based on otoliths) varied from 20 to 57 days for 23 chaetodontid fishes in a study by Leis (1989).  The duration of the pelagic stage is unknown specifically for the raccoon butterflyfish.  However, Watanabe (1946 in Leis 1989) documented that larvae measured <15.5 mm at settlement.