News / Species Spotlight / Revisited Dwarf Angelfish (11/12/14)

Revisited Dwarf Angelfish



by Charles J. Hanley III

Scientific Name: Centropyge spp.
Common Name(s): Dwarf or Pygmy Angelfish (collectively)

Taxonomy:

Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Pomacanthidae
Genera: Centropyge

Description:

Few fish species offer a better combination of attributes than the Dwarf, or Pygmy, Angelfish of Genus Centropyge. These smallish fish exhibit flashy combinations of yellows, oranges, blues, and purples that are impossible to ignore. Once established, they are relatively hardy and peaceful, and have become quite popular amongst fish- and reef-keepers alike. Of course, no fish is perfect, but pygmy angels are not far off. Fortunately, the pros heavily outweigh the cons.

There are at least 26 described species of Centropyge angelfish, though many are not commonly dealt with in the aquarium trade. The most common pygmy angelfish sold as livestock include:


African Pygmy Angelfish (C. fisheri)
Cherub/Cherubfish (C. argi)
Colins (C. colini)
Coral Beauty/Dusky/Two-Spine (C. bispinosus)
Eibls/Blacktail (C. eibli)
False Lemonpeel/Heralds (C. heraldi)
Flame (C. loriculus)
Flameback (C. aurantonotus)
Lemonpeel (C. flavissimus)
Multicolor (C. multicolor)
Potters/Russet (C. potteri)
Rusty (C. ferrugatus

Most pygmy angelfish look fairly similar to one another, in terms of overall body shape. Only a few exceed several inches, and it is rare to encounter a specimen larger than about six. They are ray-finned fish (Class Actinopterygii) that appear tall and slender when viewed from the front. By contrast, the side view of the body gives the impression of a spade, but the body itself is actually oblong. The head and caudal peduncle are much narrower than the back, yet the fins are shaped such that they flare out in a spade-like formation. The tail is usually truncate, giving the posterior end of the fish a squared-off appearance. Two of the most characteristic features of marine angelfish are, in general, the presences of course edged ctenoid scales and a prominent operculum spine, and pygmy angels are no exception. Finally, most pygmy angels demonstrate a slightly inferior mouth shape, which means that their upper jaw extends out further than their lower. In other words, they have an overbite.

In most fish species, the shape of the mouth is indicative of its feeding habits. Pygmy angels appear to have an overbite because that morphology favors their natural inclination towards grazing. Centropyge angels are well-known to prefer algae, especially of the filamentous variety. They also eat small invertebrates like crustaceans, tube worms, and sponges. They have even been known to pick at the tissue of corals, though that habit may depend as much on the individual as it does the species.

Color is another quality that can vary within a species, as well as between. Deep royal blues and rich purples are commonplace, and are often offset by stark canary yellow. There are a number of species which exhibit this color combination, but the shape, positioning, and proportion of each color are classifying features. In other species, such as coral beauties, Potters, flames, and rusties, scorching shades of orange add an intriguing color element to the overall package. In the cases of the lemonpeel and false lemonpeel/Heralds angels, the coloration is almost exclusively yellow. Even more stunning is the glowing neon appearance of many of these colors, making some pygmy angels look as if they are electrified!



Natural Habitat and Ecology:

They majority of pygmy angelfish hale from the Indo-Pacific basin, but Red Sea and Caribbean species are also known and collected. In general, the requisite habitat for these diminutive fish is similar across the board, though depth profiles can vary from 1 to 90 meters. They are most common on seaward sides of reefs, as well as in coral lagoons. Preferred substrates are loose rocks, coral rubble, and branching hard corals such as Acropora species. In some cases, pygmy angels are found on deeper reef slopes, where the substrate is more horizontal than vertical.

More important than the material of the substrates are their shapes. Pygmy angelfish typically prefer areas with many hiding places. Branching corals, rock crevices, and coral caves all provide excellent cover for these fish, which will establish and defend a home territory. Moreover, they need nooks and crenulations within their territory to satisfy their active metabolisms. Healthy pygmy angels will pick invertebrates and filamentous algae off the rocks throughout the day, ceasing feeding only when they go to sleep for the night.

During the day, pygmy angelfish may be seen individually, or in small groups of 4 to 6. Their grouping habits are particularly significant, as they play a strong role in the reproductive cycle of these fish. They are what are known as protogynous hermaphrodites, which means that they are capable of changing sexes in the middle of their lives. During their larval stage there is no sexual assignment, but as they mature, all angelfish become females. Female angelfish group together in small schools that are called harems, and each is attended by one male. The male, fascinatingly enough, was once a female. At a point when the harem needs another male, for instance if the previous one is killed defending its territory, the dominant female morphs into the new male and assumes its duties. In this manner, angelfish are fecund reproducers. This particular social hierarchy allows the majority of the population to be breeding females. At dusk during the spring and summer, the male courts one of his females and he fertilizes her eggs as she broadcasts them into the water column. Each egg is equipped with a buoyant oil droplet which propels it to the surface; after a brief 24-hour incubation period, the larval angelfish hatches out and lives planktonically for its first month.



Aquarium Care:

When caring for the Centropyge pygmy angelfish, the first thing to consider is food. Pygmy angels are sometimes picky eaters, though they can usually be converted to prepared foods with relatively little trouble. Upon introduction to their new surroundings, it may be several days before the fish decides to accept meals. As such, it is a good idea to be sure to provide adequate amounts of well-established live rock. The live rock will not only provide countless invertebrate meal opportunities, it will also create hiding spaces and help the angelfish quickly establish a home territory. If the pygmy easily establishes said territory, has a safe place to hide, and can find foods on its own, it will be more likely to make the adjustment and begin to feel comfortable. A comfortable fish, generally, will be far more amenable to accepting prepared foods. The ideal diet for pygmy angelfish consists of omnivorous offerings of algal sheets, planktonic crustaceans, and naturally-occurring copepods. Pygmy angels can sometimes be coaxed to eat flake and pellet foods as well, so offering a variety of menu items will yield the highest rates of success.

Not surprisingly, another important consideration for pygmy angel care is water quality. Natural reef tank conditions are ideal, because the clean water conducive for coral growth will also help to keep these sensitive fish healthy. Accordingly, a good regime of protein skimming and heavy bio-filtration (ideally via live rock) is a great asset for pygmy angelfish keepers. As always, UV sterilization is enormously beneficial in marine fish husbandry, especially for animals like angelfish. They are particularly sensitive to deparasitic copper-treatments, so alternative methods of treatment are preferable. In addition, it is always a good idea to quarantine new fish to ensure that no pests are introduced into display systems.

Pygmy angelfish make good tank inhabitants, but may not be suitable for all situations. Fortunately, pygmy angels are very tolerant of other kinds of fish and will not harass those they do not resemble. However, they are small enough to be eaten by a number of predatory fish, including lionfish, groupers, and moray eels. As such, pygmies should be kept only with fish that are disinclined to dine on other fish. Conspecifics, as well as comparably-colored species, do not always get along either; these fish will need kept completely separate from analogs, in previously established pairs, or in a large tank that is sparsely populated by similar looking fish. In captivity, pygmy angelfish are known to form mating pairs, and may spawn nightly. Regrettably, the floating nature of their eggs cause them to be rapidly removed the system via protein skimming and mechanical filtration. Without specially set-up breeding tanks, captive rearing of pygmy angels is difficult or impossible. It is rarely achieved and most specimens available to hobbyists are wild-caught.

Since cultured animals are hard to come-by, it is especially important to evaluate pygmies with a critical eye prior to purchase. Due to the depth at which some are collected, they may suffer ailments associated with decrompression, including infections from punctured swim bladders. Healthy animals will swim actively, with their heads held higher than their tails. Look for fish that are lesion-free, brightly-colored, and hungry. They must be very willing to eat while at the store, where they should be held successfully for several weeks before being sold.

Take care when introducing pygmies into reef tanks, where individuals have been known to pick at scleractinian corals, anemones, sponges, and feather duster worms. There is no way to predict whether a given fish will attempt to eat decorative invertebrates, so they cannot be said to be completely reef-safe. At the same time, many aquarists (myself included) have been able to keep pygmies in coral tanks without any problems. There is reason to believe that well-fed specimens will be less likely to eat corals and other sessile invertebrates, but there is no guarantee. With that said, it must also be noted that reef tanks are the most optimal environments for successful pygmy care. The live rock aquascapes typically found in coral tanks mimic the natural environment of these fish, providing both hiding spots and food.

With a modicum of attention-to-detail, pygmy angelfish do very well in captivity. Their small size makes them perfect for tanks as small as 30 gallons, and in some cases even smaller tanks will suffice. The colors they exhibit are virtually unsurpassed, and they will rival any wrasse in a beauty contest. Choose one carefully, and with a little luck you will have a great new pet.





Works Cited:

Lieske, E. and R. Myers. Coral Reef Fishes, Revised Edition. Princeton University Press: Princeton. 2002.

Michael, S. AQUARIUM FISH: Colin's Angelfish (Centropyge colini). Advanced Aquarist Online Magazine. Dec. 2004. URL: < http://www.advancedaquarist.com/issues/dec2004/fish.htm >

Miller, L. Potter's Angelfish, Centropyge potteri. Reefkeeping Magazine Online. Mar. 2009; 8: 2. 2009. URL: < http://reefkeeping.com/issues/2009-03/fish/index.php >

Mondadori, A (editor). Simon & Schusters Guide To: Freshwater and Marine Aquarium Fishes. Fireside: New York. 1977.

Muniandy, I. Flame Angelfish. Article Base Online. 2010. URL: < http://www.articlesbase.com/pets-articles/flame-angelfish-1668071.html >

Nelson, J.S. Fishes of the world, Third edition. John Wiley & Sons, Inc.: New York. 1994.

Talbot, R. Beginner Dwarf Angelfish, Essential Statistics on Pygmy Angelfish. Suite 101 Online. 2008. URL: < http://fishinsects.suite101.com/article.cfm/beginner_dwarf_angelfishes >

Tullock, J.H. Marine Angelfish. American Marinelife Dealers Association Online. 2003. URL: < http://www.amdareef.com/ho_angel_info.htm >

Wolfenden, D. The African Pygmy Angelfish and Three Alternatives. Practical Fishkeeping Online Magazine. 2010. URL: < http://www.practicalfishkeeping.co.uk/content.php?sid=2775 >