Marine Angelfish

By John H. Tullock
Copywright ©1996 All rights reserved

Marine angelfish constitute the Family Pomacanthidae, which, for the ichthyologically challenged, is a reference to the spines (acanthus) borne on the opercle and elsewhere on the head. They are closely related to the butterflyfishes, Family Chaetodontidae, and once were included in the same family. Angelfish have the rough-surfaced ctenoid scales, increasing their “spininess” and, of special interest to aquarists, their ability to become entangled — and often seriously injured — in nets.

All angelfish species thus far studied, several dozen in all, are protogynous hermaphrodites, meaning that all individuals begin life as females, with mature, larger individuals becoming male. All are also haremic, with a single male defending a territory containing two to five females. These territories can range from an area the size of a bathroom to one larger than a two-car garage.

All angelfish thus far observed spawn in a similar fashion, with the pair engaging in a courtship ritual that terminates in a rush toward the surface, at which point eggs and sperm are released. Spawning typically occurs at sunset, and the nearly microscopic larvae that hatch out the next evening swim in the plankton for about a month. Members of the genus Centropyge, arguably the best choices for aquarium fish, routinely form pairs and spawn, often daily, in captivity. Maintaining two to three females with a single male, or rearing three small fish together and allowing their gender determination to sort itself out naturally, usually produces the desired result in a large, well-maintained aquarium. All efforts to rear the larvae have so far been unsuccessful. Artificial rearing of larval Pomacanthus species from Florida was carried out successfully years ago by Martin Moe at his Aqualife Research Corporation. However, Moe was not able to produce angelfish and make a profit, and, to my knowledge, no one else has since succeeded in the endeavor. Thus, all angelfish available in the aquarium trade are collected from the wild. The condition in which specimens arrive in the shop thus greatly influences their subsequent survivability, as does the choice of species. Some simply do not adapt to the aquarium, while others do so easily.

Marine angelfish genera differ in size, diet and behavior, and these factors significantly affect the suitability of a particular species for the aquarium. Here are the basics for each of the genera commonly seen in the trade:

Apolemichthys, represented by the flagfin (A. trimaculatus) and golden spotted (A. xanthopunctatus), range up to about six to eight inches in length. They feed on benthic invertebrates such as sponges, and adapt poorly to aquarium diets.

Far better are the numerous species of Centropyge, commonly known as “dwarf angelfishes.” From Florida and the Caribbean comes C. argus, the pygmy angelfish, which, at under three inches, is suitable for tanks as small as 30 gallons. It feeds primarily on filamentous algae, and the small invertebrates living within the tangle of filaments. The flame angelfish, C. loriculus, is known from Hawaii, but most specimens in the trade come from Christmas Island. These robust little fish, seldom reaching four inches, feed on algae and a variety of other readily available foods and are highly recommended. Commonly imported species include C. bicolor (bicolor), C. flavissimus (lemonpeel), C. heraldi (false lemonpeel, Herald’s), and C. bispinosus (coral beauty). Others are imported from time to time, with rare species commanding a high price. There are 26 species of Centropyge (and probably more) in the Indo-Pacific.

The genus Genicanthus includes several interesting species which, according to Myers (1989) “do well in the aquarium but many of the species are rare and deep-dwelling.” In these angels, the sexes are strikingly different in appearance, whereas in most others the differences are hardly noticeable or absent. Further, they feed on plankton in relatively open water, while most other angels stay close to the reef. Plankton-eaters are usually good aquarium fish, but these have a poor record. Many dealers suspect the problems may be due to poor collecting and handling procedures.

The beautiful regal angelfish, Pygoplites diacanthus, also has a dismal record in the aquarium, probably because its diet of sponges and tunicates if difficult to duplicate in captivity. Similarly, the Singapore angelfish, Chaetodontoplus mesoleucos, has a poor record of aquarium survival, even though it supplements its diet of sessile invertebrates with seaweeds.

Large angelfishes are much less popular with hobbyists today than they were a decade ago. Part of the reason is the recent emphasis on minireef aquariums, in which the species of Pomacanthus and Holocanthus would wreak havoc, owing to their large size and propensity to eat benthic invertebrates, including, sometimes, coral polyps. This also makes many of them difficult to maintain, which is a shame, because they are among the most beautiful fish in the sea. In this group are the blue-girdled (P. navarchus), blue faced (P. xanthometapon), emperor (P. imperator), Koran (P. semicirculatus), French (P. paru), queen (H. ciliaris), and rock beauty (H. tricolor) angelfishes. They range from adaptable, in the case of the emperor, Koran, French, and queen to impossible, in the case of the others. Best results are obtained when the aquarist begins with a three to four inch juvenile specimen, providing it with a roomy tank of more than 100 gallons capacity and a diet rich in seaweeds, various seafoods, and living benthic invertebrates. The latter seem especially important for long term success with these species. Some collectors will also collect appropriate sponges and tunicates for feeding these fishes, which, for obvious reasons, are of interest today primarily to advanced hobbyists.

Advances in hatchery technology, coupled with a reduced availability of wild-caught specimens, may make captive-propagated angelfish a reality for the aquarium trade in the near future. Sources report intensive research in this area, since many species are already popular despite their higher-than-average cost. Until that time, choose carefully from the available offerings. You may find, as many dealers do, that a few species of Centropyge are your best sellers.

Ten Tips for Success with Marine Angelfishes:

1. Small species, such as any of the Centropyge angels, adapt best to the aquarium.
2. Larger angels, such as Pomacanthus and Holocanthus species, need tanks of 100 gallons or more capacity.
3. All angelfish species demand excellent water quality. Even small amounts of ammonia or other toxic substances are harmful. They are thus generally recommended for aquarists with some experience.
4. Angelfish are easily intimidated by their tank mates, especially if the latter are established residents of long standing. To overcome this problem, the angelfish should be introduced to the aquarium in darkness. Feed the other fish well before turning out the lights, and make sure the aquarium has plenty of hiding places, at least one for each resident fish.
5. The most common reasons for angelfish mortality are poor water quality, followed by improper diet. Species that feed on benthic invertebrates have difficulty adjusting to a captive diet.
6. Pomacanthus and Holocanthus angels adapt best to aquarium conditions when obtained as juvenile specimens. In both genera, the juveniles differ markedly in coloration from the adults.
7. Centropyge species will form pairs and spawn in a large aquarium if introduced as small specimens in a group of three to five individuals.
8. Besides filamentous algae, feed Centropyge frozen, chopped seafoods and live or frozen brine shrimp.
9. Provide Centropyge angels with a tank of 30 gallons or more.
10. It may be difficult or impossible for different species of angelfish to be accommodated in the same aquarium. The best approach is to limit each tank to a single species. However, Centropyge angelfish seldom bother their tank mates, and can be included in a minireef aquarium with other fishes suited to the same environment.

Reference:  Myers, Robert F. (1989) Micronesian Reef Fishes. Coral Graphics, Guam. 301 pp.