Pomacanthus annularis
Blue ring angelfish
(Also: Blue-ringed angelfish; Bluering angelfish; Blueringed angelfish; Ringed angelfish; Ringed angle fish)

Pomacanthus annularis live in the Indo-Pacific region ranging from Sri Lanka to the Solomon Islands and from the Philippines to the northern tip of Australia. Normally this range is from 25 degrees north to 25 degrees south (Agbayani, 2002; Heemstra, 1986).

P. annularis is a tropical, marine (salt water) fish that lives around coastal rocky coral reefs and other hard bottom coastal areas. In their natural habitat the adults are normally found from 5-15 meters in depth, but as far down as 30 meters. The juveniles are usually at the upper range of the adults and sometimes are in even shallower water. When kept as aquarium fish, optimal temperature is 26 degrees Celsius with a pH of 8 and lots of light.

The adults of the genus Pomacanthus are normally haremic; one male defends a territory with two to five females living with the male. They are usually found alone or in pairs in caves in the rocky/coral oceanic bottom (Steen, 1978; Tullock, 1996; Agbayani, 2002).

Adult P. annularis are a dark orange to brown color with white caudal fin, grow up to 12 inches in length, head to caudal fin and are monomorphic between sexes. Soft dorsal spine rays, numbering 20-21 are at times longer than normal so that they extend further than the rest of the dorsal spine rays. There are also 13 dorsal spines with the dorsal fins being continuous, three anal spines and 20 soft anal rays (Agbayani, 2002). Adult bluering angelfish have blue, horizontal curved lines that extend from the back of the head/pelvic fin area to the dorsal and caudal fins. Also there are two blue stripes that cross the face, one through the eye and the other below. Finally, the blue ring (where it gets its common name) is above and behind the operculum (Agbayani, 2002; Nelson, 1994; Thresher, 1984; Heemstra, 1986).

Members of the family Pomacanthidae were classified until recently in a family with butterfly fishes because they share many features "such as deep compressed bodies, ctenoid scales which extend out onto the median fins, a small mouth with brush-like teeth. But differ from butterfly fishes, however, in having a long spine at the corner of the preopercle (also smaller spines on the preopercle, opercle, and preorbital) (Allen, 1994). Other differences include the presence of a snout in angelfish and a pelvic axillary process (Helfman et al., 1997).

The larvae hatch at sunset the day after the courtship ritual of the parents and swim with the plankton for a month before developing into juveniles. This type of fish is not able to reproduce well in captivity because the larvae are unable to survive. The fish are considered protogynous hermaphrodites, meaning at the beginning of life all are females. Then as development continues the larger fish become males (Tullock, 1996).

Also during development a drastic change occurs in the coloration patterns of juvenile P. annularis to the adult. The juveniles start out with alternating, vertical blue and white stripes on a black background. This coloration pattern is similar to all large angelfish and P. annularis juveniles often are misidentified as P. chrysurus. However, the caudal fin is transparent in bluering angelfish but is yellow in P. chrysurus. Then as they mature into adults, the vertical blue and white stripes disappear, the caudal fin whitens, and the background becomes a dark orange to brown. Horizontal, curved blue lines also appear and run from the back of the head/pelvic fin area to the caudal and dorsal fins (Agbayani, 2002; Heemstra, 1986).

For members of the genus Pomacanthus, spawning normally begins with the onset of dusk and is thought to be triggered by the decrease in light. However it is not known whether there is a correlation between time of year or with the lunar cycle and the onset of spawning in angelfish. The adults have a courtship ritual that ends in the male and female slowly swimming toward the surface of the water and releasing eggs and sperm. The larvae then swim with the plankton for a month before continuing development. Spawning is thought to take place between only one male and one female at a time, but males possibly mate with more than one female with in the group (Thresher, 1984; Agbayani, 2002; Tullock, 2002).

Some large angelfish, such as the P. annularis have been recorded to live up to 25 years in an aquarium (www.sphyraena.com/library/angelfish.html).

Almost all angelfish, and probably the bluering angelfish, are haremic, which means there is one male defending a territory with two to five females. This territory can be from the size of a bathroom to the size of a two-car garage (Tullock, 1996). They can often be found in caves at night or swimming for food during the day in pairs or alone (Steen, 1978; Agbayani, 2002).

P. annularis are omnivorous, eating benthic invertebrates such as zooplankton, sponges, tunicates and coral polyps. Also these fish eat ascidians, algae, weeds, and nektonic fishes (Steen, 1978; Agbayani, 2002).

The bluering angelfish is kept as an aquarium fish and is exported regularly from Sri Lanka (Ceylon) to the US and Europe (Heemstra, 1986; Agbayani, 2002).

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