Blue Ring Angelfish

The Blue-ringed Angelfish is strikingly beautiful, capturing the attention of enthusiasts and admirers everywhere!

The Blue-ringed Angelfish Pomacanthus annularis is a handsome specimen both as a juvenile and as an adult. Though juveniles are very similar in appearance to several other members of the Pomacanthus genus, the adult is easily distinguished. The adult has a vibrant blue patterning of graceful upcurving bands on top of a golden brown background. Its common name comes from the bright orange, blue rimmed eyespot above the gill cover. It is also known by the common names Blue King Angelfish and Ringed Angelfish.

The Blue-ringed Angelfish is one of the few Pomacanthus that really likes turbid waters. In the wild it is often found in harbor areas near piers and sunken ships where the water is unsettlled. This is one big angelfish, it can reach almost 18” (45 cm) in length and live for over 16 years in captivity. Tank size is very important for the angel to provide hiding places along with plenty of open swimming space. It should have a minimum tank size of 180 gallons, but optimally a 250 to 300 gallon (946 – 1,135 liters) tank is suggested. Be sure the tank is wide enough so this large angel can comfortably turn around.

This angelfish is moderately hardy with a personality resembling the family dog when happy. It makes it a good choice for the intermediate aquarist with a large tank and lots of live rock. Offering enough room to swim, but many places to hide, helps them feel secure. For the best success, purchase a juvenile between 4 to 6 inches (10 – 15 cm) in length. Initially they are quite shy, and spend a good deal of their time darting out of sight when the tank is approached. Their varied diet in nature consists of encrusted invertebrates such as tunicates and sponges. But they also pick zooplankton out of the water column which makes it a little easier to encourage them to accept aquarium foods. Once adapted they will become aggressive feeders and quickly recognize their keeper as a food source.

This angelfish is best kept in a fish only community aquarium. It is semi-aggressive and can become quite belligerent, possibly bullying more passive tank mates such as butterflyfish, batfish, and trunkfish. It can be kept as a male/female pair or with another angelfish with different coloration and size, but only if the aquarium is quite large. Interestingly these are a fish that is more likely to form bonded pairs and stay together for life. It has been observed that when pairs spend some time apart, they have a ritual of head to tail spinning to welcome each other back. They also will make grunting noises when they are excited or distressed, which is unique to angelfish.

Typically this is not a 100% reef-safe fish, even though it will do well in a coral-rich tank with sessile invertebrates. They will nip the polyps of both hard and soft corals as well as invertebrates like live shrimps. However aquarists have had some success keeping them with some of the more noxious soft corals, and some have reported success with this fish and small polyped stony (SPS) corals.

For more Information on keeping saltwater fish see:
Marine Aquarium Basics: Guide to a Healthy Saltwater Aquarium

Habitat: Distribution / Background

The Blue-ringed Angelfish Pomacanthus annularis was described by Bloch in 1787. It was first collected in the East Indies but is a wide ranging species. It occurs from coast of East Africa across the Indian Ocean to the West Pacific, including the west coast of India, Sri Lanka, Southeast Asia, southern Ryukyu Islands, Taiwan, Philippines, and Papua New Guinea to New Caledonia, and north to southern Japan.

This species is on the IUCN Red List as Least Concern (LC) with a stable population. It has a wide distribution and an overall large population, and there are no major threats identified. Other common names it is known by include Bluering Angelfish, Ringed Angelfish, Blueringed Angelfish, Blue Ring Angelfish, Blue King Angelfish, and Bluestone Annularis.

Its natural habitat is coastal and coral reefs at depths of 10 – 164 feet (3 – 50 meters), often where the water is murky. But it is also encountered in caves, in sheltered coves, underneath jetties, and will often live in harbors around piers and shipwrecks. The species will be seen alone in its juvenile stage, and these young fish are found in very shallow inshore areas where there’s filamentous algae growth on rocks and dead coral substrates. Adults are usually observed in pairs, often outside of caves. It feeds most heavily on encrusting organisms including sponges and tunicates, but will also pick zooplankton out of the water column. Other foods include benthic weeds and algae, ascidians (sea squirts), and zoobenthos animals found near the sea floor.

• Scientific Name: Pomacanthus annularis
• Social Grouping: Pairs – Found alone as juveniles, but in pairs as adults.
• IUCN Red List: LC – Least Concern – A stable population.

Description

The adult Blue-ringed Angelfish has a disc-like but higher body shape with a somewhat extended, filament type dorsal fin. Adults can reach 17.6 inches (45 cm) in length, but most available specimens are less than 8 inches (20 cm). Adults less than 14 inches (35 Cm) will be observed by most divers in their natural habitat. They can live for over 16 years in captivity with good care.

The adult is entirely yellowish brown with numerous fine dots and about 8 curving blue lines running obliquely throughout on the side. There is a rounded yellowish brown area surrounded by blue behind the eye and the face is blue with blue lines just behind eye. The dorsal and anal fins are brownish and gradually becoming deep blue posteriorly. The dorsal fin has a blackish thread from the central portion, becoming yellowish posteriorly. The caudal fin is abruptly white, gradually shading to slightly duskier with a white edge. The pectoral fins are yellowish brown with a blue-black spot at fin-base and the pelvic fins are yellowish brown with several blue-black lines.

Juveniles are blue-black with several vertical, slightly curving white and blue bands on the side that gradually increasing in number with growth. Then over time, these bands on the side of young specimens will gradually fade away as this fish matures. Their fins are blue-black except for the caudal fin, which is translucent to whitish.

Blue-ringed Angelfish (Juvenile) Photo © Animal-World:
Courtesy Hiroyuki Tanaka

Juveniles of this species are very similar in appearance to several other members of Pomacanthus that are black with white bands. Some of the Pomacanthus youths that look very similar, and also occur in the same areas in nature, are the Red Sea AngelfishPomacanthus maculosus and the Old Woman Angelfish Pomacanthus rhomboides. This juvenile is also easily confused with the young Ear-Spot Angelfish Pomacanthus chrysurus, but lacks the yellow caudal fin of the Chrysurus Angelfish.

• Size of fish – inches: 17.6 inches (44.70 cm)
• Lifespan: 16 years – Reported up have a lifespan up to 16 years in captivity.

Fish Keeping Difficulty

This angelfish is moderately hardy, but it is big and a fairly active fish, so needs a lot of space. It makes a good choice for the intermediate aquarist that can provided a minimum 180 gallon tank, though 250 to 300 gallons is optimal. The proper sized tank is paramount in importance to avoid stunted growth, which can affect the organs and muscle development of this fish, resulting in a shortened life. Even as a juvenile a tank smaller than 135 gallon should be avoided. Anything smaller will result in heightened aggression toward other fish that they otherwise would not have usually paid any attention to.

When obtaining your Blue-ringed Angelfish, the best size for adjusting to life in a captive environment is between 4-6” (10-14 cm) in length. These angelfish usually takes foods heartily if in a good condition. Juveniles will swim actively and freely, but are somewhat shy and retiring when first introduced to their new environment. It will need lots of rock work with multiple places to hide. But when acclimated, both juveniles and adults will spend most of day swimming in open areas. This fish will even venture to the surface and take foods from its keepers..

• Aquarium Hardiness: Moderately hardy – They are moderately hardy when kept in the proper size tank with plenty of places to hide and appropriate tank mates.
• Aquarist Experience Level: Intermediate

Foods and Feeding

The Blue-ringed Angelfish are omnivores, in the wild they eat large amounts of encrusting invertebrates like sponges and tunicates, as well as picking zooplankton from the water column. Almost any food will be accepted but be sure to provide a varied diet that includes substantial sponge foods, either commercially prepared mixtures containing sponge or by providing live sponge. Meaty foods, dried flakes, shrimps, and tablets are favorites but also offer frozen shrimps, prepared diets for sponge and algae eaters, vegetables, and Japanese Nori. Foods containing color enhancing qualities may be used as well. Provide adults with various foods at least twice a day and juveniles should be fed three to four times a day.

• Diet Type: Omnivore – Provide a diet with spirulina and sponge material included, color enhancing foods are also helpful.
• Flake Food: Occasionally
• Tablet / Pellet: Occasionally
• Live foods (fishes, shrimps, worms): Some of Diet – Brine shrimp, mysis shrimp, and other protein sources can be offered occasionally. They may be needed to elicit a feeding response in the beginning.
• Vegetable Food: Most of Diet
• Meaty Food: Some of Diet
• Feeding Frequency: Several feedings per day – Adults need 2 to 3 feedings a day and up to 4 times a day for juveniles.

Aquarium Care

The Blue-ringed Angelfish is rather sensitive to water quality and a large tank is important for this fish. Frequent water changes are not necessary if water quality is very high. Normal water changes of 20% a month, or 10% every 2 weeks are fine, varied according to the number of fish and the tank size. A small water change is preferable at any one time, as a sudden massive water changes can cause trouble. Keep pH at 8.0 as lower pH levels will cause declining health and eventual illness. A suggested practice is regular water testing, which will tell you when your tank needs a water change.

• Water Changes: Bi-weekly – Do normal water changes of 10% every 2 weeks, or 20% a month.

Aquarium Setup

The Blue Ring Angelfish needs plenty of room to grow. The tank should be well decorated with rocks/ corals that provide some hiding places, especially for juveniles. The juvenile can be started in a 135 gallon (511 liters) aquarium. These young fish tend to be very territorial, so this good sized tank can help deflect some of the aggression towards other fish and it will be much easier for them to hide.

As an adult a minimum 180 gallon aquarium will be needed, though a larger tank would being better. A tank that is too small can affect organ and muscle growth due to stunting, and the angelfish will be more aggressive. A known male/female pair will need a tank that is 220 gallons or more. Add the smaller of the pair first and put up a barrier between them so the larger cannot harm the smaller angelfish, then observe their behavior to make sure they will be compatible.

These angelfish enjoy rock work arranged in a way that offers a few hiding places but also leaves open areas for swimming. Keep the water quality high and provide areas in the tank with some stronger currents. Also have good lighting for the angelfish’s health. In the wild their bodies use sunlight to process vitamins from the foods they ingest. A tank with dim lighting can eventually leading to several maladies including blindness.

• Minimum Tank Size: 180 gal (681 L) – A juvenile can be started in 135 gallons, but 180 gallons or more will be needed for an adult. 250 to 300 gallons is needed to keep a male/female mated pair.
• Suitable for Nano Tank: No
• Live Rock Requirement: Typical Plus Hiding Places – Live rock with plenty of caves and other places for them to hide is necessary, especially for juveniles when initially introduced.
• Substrate Type: Any
• Lighting Needs: Moderate – normal lighting – These angelfish need enough light to stay healthy, and it will also help promote naturally growing foods on the live rock.
• Temperature: 72.0 to 82.0° F (22.2 to 27.8&deg C)
• Breeding Temperature: 0.0° F
• Specific gravity: 1.023-1.025 SG – 1.023 1.025
• Range ph: 8.0-8.4
• Brackish: No
• Water Movement: Strong – Provide at least one area in the tank with strong water movement to mimic their natural habitat.
• Water Region: All – They are open swimmers and will spend time in all parts of the aquarium.

Social Behaviors

The Blue-ringed Angelfish is an aggressive fish, especially when a juvenile, but will mellow out a little as it grows into adulthood. Selecting tank mates poses few problems as this angelfish can be kept some aggressive species. Smaller and ‘weaker’ fish such as cardinalfish, gobies, tilefish, butterflyfish, fairy basslets, fairy and flasher wrasses, etc. may be good choices. Slower moving sharks and stingrays are at risk for being picked at and harmed by the larger angelfish. Because this angelfish can be quite belligerent, possibly bullying more passive tank mates, keep a diligent eye on this type of mix. Some of the aggressive genera wrasses can be kept with it successfully. Also small but very aggressive fishes like dottybacks would also be okay to keep with an adult in most cases.

A male/female pair can be kept in a tank that is at least 220 gallons. It can also be housed with larger and rather territorial angelfishes like other Pomacanthus and Holacanthus as long as the aquarium is large enough, 250 to 300 gallons (946 – 1,135 liters) or more. The smaller angelfish Centropyge, Apolemichthys, Genicanthus, Chaetodontoplus and Pygoplites can also be good tank mates.

The Blue-ringed Angelfish is not a 100% reef-safe fish, even though it will do well in a coral-rich tank with sessile invertebrates. They will nip the polyps of both hard and soft corals as well as invertebrates like live shrimps. However aquarists have had some success keeping them with some of the more noxious soft corals. Mushroom corals are usually left alone as are anemones when well guarded by a resident clownfish. Some have reported success with this fish and small polyped stony (SPS) corals, but it will nip the polyps of gorgonians, xenia, athelia, and zoanthids. Large polyped stony (LPS) corals may also be nipped at. Invertebrates are usually fine except for clams, oysters, scallops and feather dusters. Very small shrimp like Sexy Shrimp may be nipped at, but larger cleaner shrimp should be fine.

• Venomous: No
• Temperament: Large Semi-Aggressive
• Compatible with:
  • Same species – conspecifics: Sometimes – They are very aggressive toward other angelfish unless system is very large, at 250 – 300 gallons. In a large tank they can be kept as male/female pair or with another angelfish with different coloration and size.
  • Peaceful fish (gobies, dartfish, assessors, fairy wrasses): Threat – May harass smaller peaceful fish. Most Pomacanthus are fine with these types of fish, but the Blue-ringed Angelfish is an exception.
  • Semi-Aggressive (anthias, clownfish, dwarf angels): Monitor – Provide plenty of places for these fish to hide and monitor for aggression.
  • Safe
  • Large Semi-Aggressive (tangs, large angels, large wrasses): Monitor – Slower moving sharks and stingray may be picked by larger angelfish, especially their eyes.
  • Large Aggressive, Predatory (lionfish, groupers, soapfish): Safe
  • Threat – These fish need specialized environments or they will be picked on.
  • Anemones: Safe – May nip at oral disk, but an aggressive Maroon Clownfish or other aggressive clowns like Cinnamon, etc., may solve the problem.
  • Mushroom Anemones – Corallimorphs: Safe
  • LPS corals: Threat
  • SPS corals: Monitor – Many have had success with these, but monitor for individual preferences.
  • Gorgonians, Sea Fans: Threat
  • Leather Corals: Monitor
  • Soft Corals (xenias, tree corals): Monitor – Many have had success with those from the Sinularia, Sarcophytom, Cladiella, and Paralemnalia genera, but still monitor for individual preferences.
  • Star Polyps, Organ Pipe Coral: Threat
  • Zoanthids – Button Polyps, Sea Mats: Threat
  • Sponges, Tunicates: Threat
  • Shrimps, Crabs, Snails: Monitor – Smaller shrimps, like Sexy Shrimp, may be at risk.
  • Starfish: Monitor – Will nip at appendages if not well fed.
  • Feather Dusters, Bristle Worms, Flatworms: Monitor – Will nip at feather dusters if not well fed.
  • Clams, Scallops, Oysters: Threat
  • Copepods, Amphipods, Mini Brittle Stars: Monitor – Their populations should not dwindle in the presence of the Blue-Ringed Angelfish even though it may eat these items

Sex: Sexual differences

No sexual differences are known, but adults are seen swimming in pairs in their natural environment.

Breeding / Reproduction

There are records of reproductive behavior in aquariums, and the larvae rarely survive. In the wild, the type of mating system employed by Pomacanthus is dependent on the density of the population at a particular location. In one area they may form permanent pairs while in other areas, where the species is more common, they will form harems. Each harem consists of a male defending several females in a small area. In all systems however, these fish spawn in pairs.

Pairs congregate at the edge of the reef at sunset. They often engage in a courtship display where the male and female swim in a brisk head to tail circling motion. Each pair will spawn and ascend into the water column. Swimming together in an arc up to about 7 – 10 feet (2 – 3 meters) above the substrate, they expel pelagic eggs at the summit.

See Breeding Marine Fish for a description of how they reproduce in the wild.

• Ease of Breeding: Difficult

Fish Diseases

Blue-ringed Angelfish, like other saltwater angelfish, are prone to any disease that captive saltwater environments have to offer. They are most likely to be affected if they are stressed from inappropriate housing or tank mates. This angelfish may suffer from Saltwater Ich or White Spot Disease (Crypt) and other infectious diseases.

White Spot Disease Cryptocaryon irritans, also known as Marine Ich, Saltwater Ich, or Crypt is the most common disease that is generally associated with marine tangs and angelfish. Symptoms of Marine Ick are constant scratching, culminating with lots of white dots. These dots disappear for a few days, only to return with double the number. This results in the fish suffocating from these parasites blocking the gills from providing oxygen.

Another common disease is Marine Velvet or Velvet Disease Oodinium ocellatum, (syn: Amyloodinium ocellatum or Branchiophilus maris), which is a parasitic skin flagellate. Symptoms of Marine Velvet are a peppery coating giving a yellow to light brown “dust” on body, clamped fins, respiratory distress (breathing hard as seen as frequent or quick gill movements), cloudiness of eyes, glancing off decor or substrate, and possible weight loss.

Parasites on marine fish kept with live rock or in any type of reef environment can be extremely difficult to treat. Typical treatments like copper and formalin solutions, as well as quinine based drugs are harmful to other marine creatures. However drugs such as metronidazole provide an effective and safe treatment for several protozoan and anaerobic bacterial diseases. Metronidazole works by ceasing the growth of bacteria and protozoa. Metronidazole is an antibiotic for anaerobic bacteria with anti-protozoal properties. This drug is reef safe, and medications are either added to the water or mixed with the fish food. Some available products that contain metronidazole include Seachem Metronidazole, Seachem AquaZole, Thomas Laboratories’ Fish Zole and National Fish Pharmaceutical’s Metro-Pro.

For external parasites you can slowly increasing the temperature of your tank to at least 82° F (28° C). That will prevent the parasite from completing its life cycle which includes the attachment to fish. A further combination of the higher temperatures with medicated food will provide timely relief. The Seachem Metronidazole medications works well in combination with another Seachem product called Focus, which is a bonding agent. This treatment can be used in a reef aquarium since the medication is bound to the food, which even if the corals eat, will not hurt them. Mix Focus in a ratio of 5 to 1 with their Metronidazole (5 parts Focus to one part Metro), then mix this with 1 tablespoon of food. Feed the medicated food to the fish 3 times a day for at least a week or until symptoms are gone.

For more information on diseases that saltwater angelfish are susceptible to, see Aquarium Fish Diseases and Treatments.

Availability

The Blue-ring Angelfish is occasionally available at pet stores or can be found online, they are fairly expensive.

References

• Animal-World References: Marine and Reef
• Pomacanthus annularis (Bloch, 1787) Bluering angelfish, Fishbase
• Pomacanthus annularis, IUNC Red List, International Union for Conservation of Nature and Natural Resources
• Helmut Debelius, Rudie H. Kuiter, World Atlas of Marine Fishes, Hollywood Import & Export, Inc., 2006
• Scott W. Michael, Angelfishes & Butterflyfishes: Reef Fishes Series , Microcosm Ltd, 2004
• Mark Allen, Roger Steene, Gerald R. Allen, A Guide to Angelfishes and Butterflyfishes , Odyssey Publishing, 1998
• Dr. Warren E. Burgess, Dr. Herbert R. Axelrod, Raymond E. Hunziker III, Dr. Burgess’s Atlas of Marine Aquarium Fishes, T.F.H Publications inc., 1990
• Roger Steene, Gerald R. Allen, Hans A. Baensch, Butterfly and Angelfishes of the World, Volume 1, John Wiley & Sons, 1980
• Jim McDavid, Large Angels in the Home Aquariums, Part 1, Advanced Aquarist, Pomacanthus Publications
• Jim McDavid, Large Angels in the Home Aquariums, Part 2, Advanced Aquarist, Pomacanthus Publications
• Bob Goemans, Pomacanthus annularis, Saltcorner Aquarium Library
• Frank Schneidewind, Kaiserfische, (in German) 1999.