Paracanthurus hepatus
FAMILY
Acanthuridae
TAXONOMY
Paracanthurus hepatus Linnaeus, 1766, Ambon and Molucca islands, Indonesia. Western Atlantic localities are in error.
OTHER COMMON NAMES
English: Blue tang, hippo; German: Paletten-Doktorfisch.
PHYSICAL CHARACTERISTICS
The body is compressed and somewhat disc-like; it elongates with growth. The caudal fin is truncated in adults, but slightly rounded in juveniles. There are nine spines and 19–20 soft rays in the dorsal fin, three spines and 18–19 soft rays in the anal fin, 16 soft rays in the pectoral fin, and one spine and three soft rays in the pelvic fin. The caudal peduncle has a single folding spine on each side. The body is a vivid bright blue, and the belly is a paler shade of blue or, in Indian Ocean specimens, yellowish blue. A black band curves backward from the eye to the caudal peduncle. A second black band runs back along the middle of the body from just behind the pectoral fin and joins the upper band just before the caudal peduncle. The caudal fin is mainly yellow, the yellow arising just ahead of the caudal spine, with black margins that arise at the caudal peduncle. Grows to 10.2 in (26 cm) in length.
DISTRIBUTION
Tropical and subtropical waters of the Indo-West Pacific, from East Africa east to Micronesia, the Line Islands, and the Samoa Islands, north to Kochi Prefecture in Japan, and south to northern New South Wales, Australia. Observations of this species in Hawaiian Islands are attributed to releases of aquarium stock.
HABITAT
Outer coral and rocky reefs and channels in clear water areas with strong or moderate current. Juveniles and subadults prefer
to shelter in shrublike corals. Not common and patchy in distribution wherever it occurs. Depth range of 6.6–131 ft (2–40 m).
BEHAVIOR
Occurs in small aggregations that hover 3.3–6.6 ft (1–2 m) above the substrate.
FEEDING ECOLOGY AND DIET
Omnivorous. Feeds on zooplankton and benthic algae.
REPRODUCTIVE BIOLOGY
Reproductive biology is not well known. Courtship probably is paired or paired within a spawning aggregation. Eggs and larvae are pelagic, with a larval life in excess of 37 days.
CONSERVATION STATUS
Not listed by the IUCN. Localized populations are vulnerable to overfishing of juveniles for the aquarium trade.
SIGNIFICANCE TO HUMANS
Collected for the aquarium trade, in which it is highly prized. Juveniles and subadults that shelter in corals are relatively easy to collect.
