The Rock Beauty Angel with its contrasting colors of black and yellow is truly a strikingly “beauty”!

The Rock Beauty Angelfish Holacanthus tricolor is very handsome fish and easily distinguished from other angels. This eye-catching beauty has a black body contrasted with a bright yellow head and tailfin, and a distinctive yellowoutline to its fins. Some adults even have black lips! It is one of the smaller of the Holacanthus genus, typically reaching only about 8 – 10 inches (20 – 25 cm) in length. In fact it is the smallest angelfish in the Atlantic Ocean except for dwarf angelfish species, and the most common.

The adorable juveniles are all yellow, but with a black spot trimmed in bright blue on the upper back. This spot is likely imitating the similarly colored eye, which helps to confuse predators. As they mature the black spot expands until it covers most of the body. The coloring of these juveniles is very similar to the Threespot Damselfish Stegastes planifrons, which occurs across the same range. However the damsel has a more elongated body while the angelfish is rounder, and the angel lacks another small spot on the top of the caudal fin base.

The coloration isquite striking, but along withthese good looks are additional benefits for the Rock Beauty. Their appearance allows them to blend in with the rocks and rubble of the coral reefs where they live. They stay very close to the reef structure for their entire lives and become quite territorial as they defend their home. Thus it is commonly called the Rock Beauty, but is also known as the Yellow Nanny Angelfish, Corn Sugar Angelfish, and Coshubba. Juveniles are commonly found among MilliporaFire Corals, which are a “stinging coral” that can cause a burning sensation if touched. Divers and snorkelers need to exercise caution and wear gloves when anywhere near these corals.

These angelfish can be a challenge to keep due to their nutritional needs as adults, and are really only suited for advanced aquarists. Although juveniles are easier to feed, eating more algal type foods, adults are very dependent on sponge material for nutrition. Because they are a smaller size one would think a smaller tank would be fine, but the dietary needs of this angelfish dictate a larger tank. They are also timid fish that needs a calm environment and plenty of caves and crevices within rockworkfor places to hide. They need a mature tank of at least 100 gallons that has live rock with lots of encrusting sponge material and plenty of algae growth to help them adjust and to maintain them. A varied diet that includes sponge material specifically designed for marine angelfish has been suggested as well to make sure they get their needed nutrients.

They can be kept in a fish community, but juveniles will often be seen picking at other fish. They are not removing parasites as some of their Holacanthus cousins are known to do, but are actually nipping at the slime that the fish are producing. This behavior has been mistaken as aggressive behavior, but it is more of a nutritional need than a desire to dominate other fish. However they have been known to actually terrorize Blue Chromis Chromis cyanea with this behavior, due to the large amount of body slime these damsels produce. In the wild juveniles are seen nipping at the copious amounts of mucous that the Goldentail Moray Eel Gymnothorax miliaris produces.

Their territorial nature puts them at odds with any other angelfish in an aquarium. Housing them with fish that are larger or smaller is the best choice. Adults will pick on similar sized fish such as wrasses, batfish, butterflyfish and sweetlips, but smaller benthic fish are ignored in larger aquariums. They are not considered reef safe as corals will be nipped at, but invertebrates such as cleaner shrimp, snails, and crabs are generally left alone.

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

Large Rock Beauty Angelfish (Holacanthus tricolor)

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Rock Beauty

Picture of adult in dealers tank. Good quality film, but sad the fish has no place to hide.

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Perciformes
  • Family: Pomacanthidae
  • Genus: Holacanthus
  • Species: tricolor
Rock Beauty Angelfish – Quick Aquarium Care
  • Aquarist Experience Level: Advanced
  • Aquarium Hardiness: Difficult
  • Minimum Tank Size: 100 gal (379 L)
  • Size of fish – inches: 13.8 inches (35.00 cm)
  • Temperament: Semi-aggressive
  • Temperature: 72.0 to 82.0° F (22.2 to 27.8&deg C)
  • Range ph: 8.0-8.4
  • Diet Type: Omnivore
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Habitat: Distribution / Background

The Rock Beauty Angelfish Holacanthus tricolor was described by Bloch in 1795. It is found in the tropical west Atlantic Ocean from the coast of Georgia in the United States then south and all the way around Florida and to Bermuda, thenfrom the northern part of the Gulf of Mexico south to Santa Catarina and Brazil. This species is on the IUCN Red List as Least Concern (LC) as it has a large population with a wide distribution and no threats are currently identified.

This species of angelfish was first put into the genus named Chaetodon, with its original scientific classification being Chaetodon tricolor, but it was later moved to the Holacanthus genus. Another synonym also used in the past for this fish was Pomacanthus tricolor. Other common names they are known by include Rock Beauty, Yellow Nanny, and Corn Sugar, all of which have to do with habitat and color. This angelfish has been known to occasionally hybridize with the King AngelfishHolacanthus passer. Some rare hybridizing has also occurred between this angelfish and the Queen AngelfishHolacanthus ciliaris.

The Holacanthus genuscontains some of the largest angelfish species, and they are all sought after for their elegance and beauty. Holocanthus is Greek for “full thorn†which is descriptive of this genus’ physical attributes. At one time or another this genus contained over 60 of the approximately 86 marine angelfish species. Today however, after much re-classification, there are only 8 species contained in this group and all but one of these are found near the Americas. The Guinean Angelfish or West African Angelfish Holacanthus africanus is the only one that is a West African species. Of the other 7 species, 3 are found in the tropical east Pacific Ocean and 4 are found in the tropical west Atlantic.

The Holacanthus angelfish require very large aquariums ranging from 125 gallons to well over 300 gallons, and they have a specialized diet that needs to include sponge material.Except for one species, these angelfish aresome ofthe most adaptable to captivity when provided with the proper environment and foods. The only exception is this species, H. tricolor, which adapts poorly and will often starve to death. In generaly they are well suited for very large fish only aquariums andcan be kept with other species of large angelfish, surgeonfish, and triggerfish as tankmates. However none of these marine angelfish are considered reef safe as they will severely nip at all types of sessile invertebrates.

The Rock Beauty Angelfish are a diurnal species, meaning they are active during the day and sleep at night. They inhabit rock jetties, reef rubble, and coral reefs at depths from 3 feet to more than 295 feet (1 – 90+ m). They spend much of their time during the day hiding in cracks and crevices and are particularly common on seaward reef slopes and dropoffs that have abundant growths of sponges and gorgonians.

These angelfish are all born female. Small juveniles are typically solitary and are found in shallow water living among MilliporaFire Corals. Juveniles are very timid, spending most of their time hiding in rock crevices and shells. They are very territorial, rarely venturing more than a few feet from their protective shelter, and even as adults they establish and defend territories on the reefs.

The male angelfish will have harems and will defend a territory with two or four resident females. The sub-adults may be allowed to occupy the same area as an adult female within a harem. A small sub-adult female is allowed by the larger female to inhabit the territory as long as she is less than 15% of the adult females length. It is thought that if the male dies, one of the largest females will then turn male, and the smaller female will then assume a roll in the harem as a spawning female.

These angelfish feed on tunicates, sponges, zoantharians and algae. The juveniles are not known to be cleaner fish as other Holacanthus species are. They will eat similar foods as the adult, yet also feed on the mucous of some fish and eels such as the Goldentail Moray Eel Gymnothorax miliaris.

  • Scientific Name: Holacanthus tricolor
  • Social Grouping: Harems – As small juveniles they are solitary. As adults one male usually defends a territory where two to four females reside. Smaller sub-adult females will be allowed to dwell in adult female territories.
  • IUCN Red List: LC – Least Concern – A stable population.


The adult Rock Beauty Angelfish is an oblong fish with a flat, deep body while juveniles are rounder with only a slightly elongated flat body. Mature adults develop beautiful trailing filaments on the dorsal and anal fins, as well as on the upper lobe of the tailfin. This angelfish is one of the smaller Holacanthus. Itcan grow to about 13 3/4 inches (35 cm) in length, but typically only reaches between 7.8 – 10†(20 – 25.4 cm). Spawning females will reach sexual maturity at 3.9 inches(10 cm), but mature males are 8 inchesor larger. The Holacanthus angelfish can live for 20 or more years in captivity with good care.

Males are larger than the females found in their individual harems. Some males can be smaller than other males from other harems, but interestingly, the females in each harem will always be smaller than the males in each grouping. Although most caught for the aquarium trade tend to be female, size is not always an indication of sex due to this variation.

The adults have a large black area covering most of the body and onto dorsal and anal fins.The face is yellow back to the pectoral fin, the tailfin is yellow, and the edges of the dorsal and anal fins are trimmed in yellow, sometimes with a hint of orange. The only other color is the two bright blue lines on the upper and lower iris of the eye. Males will have faint red spots on the tailfin, and their faces will turn dark during courtship.

Juveniles are all yellow except for a black dot with a bright blue ring around it located near their upper back. This false “eye†is thought to help protect the juvenile from predators. The spot will gradually expand as the fish grows, until it covers the back two-thirds of the fish as an adult.

  • Size of fish – inches: 13.8 inches (35.00 cm) – They can reach almost 14†(35 cm) in length, but typically grow between 7.8 – 10†(20 – 25.4 cm).
  • Lifespan: 20 years – Holacanthus angelfish can have a lifespan of 20 years or more with proper care.

Fish Keeping Difficulty

The Rock Beauty Angelfish can be difficult to keep due to their dietary needs, collection practices, and sizing. They are suggested for advanced aquarists as many simply do not make it in captivity. Unlike other Holacanthus this angelfish does not always adapt to aquarium foods, and if they do, long term care can be a challenge. Some will seem to be fine for awhile and then all of a sudden will darken and die. A juvenile can be kept a little easier than an adult as they do not need the larger amount of sponge material that the adult requires.

One step toward being able to keep them for any length of time is to have a specimen properly collected. The ideal way to obtain a specimen would be to find a diver who handles them gently, does not use cyanide or other chemicals, and will bring up deeper specimens gradually. Finding a diver may not be too difficult as there are some people that live in Florida, who do this for a living.

However you can also be successful choosing one from a pet store. Make sure to get the right size, a specimen between 3 to 4 inches (7.6-10 cm) is best. Older fish will not accept aquarium foods and younger ones will starve and stress from the whole ordeal of collection and shipping. Ask to see the fish eat. Check to see that it does not have tears in the fins, discoloring of any kind on the body or fin bases, and is brightly colored. It should be alert and active with no fin clamping. A quarantine period is not suggested for this fish because of the stresses they endure before reaching your tank.

Some suggestions from those who have had success in keeping this fish include adding the new specimen to a very well established tank with live rock collected from Florida and the Caribbean. Make sure the rock has lots of hiding places and natural foods. The tank needs to be at least 100 gallons or more (wider is better than taller) to provide foods for a small 3-4†fish. If it grows to adulthood, move it into a 200 gallon tank to have plenty of live rock to provide enough of their natural foods. Basically foods growing on the live rock is what is feeding your fish, you are supplementing.

  • Aquarium Hardiness: Difficult – They need a large tank (100 – 200 gallons) with very mature food producing live rock. Rock from Florida and the Caribbean is strongly suggested. Tank mates should be peaceful and from same bio-type.
  • Aquarist Experience Level: Advanced – Aquarist needs to meet this angelfish’s stringent requirements, and yet success is still not guaranteed.

Foods and Feeding

The Rock Beauty Angelfish is an omnivore. In nature they eat tunicates, sponges, zoantharians and algae, and juveniles will nip at the slime coat of other fish. The green macroalgae they feed on in the wild includes Halimeda sp. and Mermaid’s Fan Udotea sp., though not Caulerpa. In the aquarium you can offer prepared foods with sponge material added and a wide variety of vegetables, especially for adults. Offering 2 to 3 feedings a day to supplement the live rock foods in the tank.

The quality of the food is important and any flake or pellet foods you choose should contain sponge material and Spirulina. Try finding algae, sponge, and sea squirts that are “meant†for humans at oriental grocery stores. They love Nori, dried algae sheets, and frozen preparations. They can also be offered fresh uncooked broccoli which will provide them with vitamin A and C. Adding caulerpa to the tank may also be appreciated. There are several good commercial foods available as well, including Formula II and Angel Formula.

Use meaty foods sparingly. If you have carnivorous fish housed with your Angelfish, feeding the tank with vegetable and sponge based foods first to give your angelfish their fill. Thus when meaty foods are added, the angelfish will be full and will not consume high levels of meaty foods.

  • Diet Type: Omnivore – Provide foods that have mostly sponge material and some spirulina algae in the formula. Offer more sponge and vegetable foods than meaty foods.
  • Flake Food: Occasionally
  • Tablet / Pellet: Occasionally
  • Vegetable Food: Most of Diet – Vegetable and sponge material should make up the majority of their diet.
  • Meaty Food: Some of Diet – Offer very little and typically only as a treat.
  • Feeding Frequency: Several feedings per day – Small amounts 2-3 times a day to supplement naturally growing foods on the live rock.

Aquarium Care

These angelfish need very good water quality. Anything below acceptable levels will result in stress which can lead to several illnesses. Water changes of 10-15% should be performed every 2 weeks for best results in 100 gallon tanks. In tanks over 250 gallons (940 l), water changes of about 30% every 3 – 4 weeks should work fine to keep the water quality high. With tanks that are very mature you may get away with more time in between water changes, but only if the tank shows no ammonia or nitrite and has very low nitrates (less than <10).

As with all angelfish, the pH level should never drop below 8.0. Controlling pH levels is best resolved by water changes rather than chemicals. Using testing equipment is suggested to tell you when to do a water change.

  • Water Changes: Bi-weekly – Suggested water changes of 10-15 % bi-weekly for a 100 gallon tank, with less needed for larger 250+ gallon tanks and very mature aquariums.

Aquarium Setup

The Rock Beauty aquarium should be is at least 100 gallons (379 l) or more for smaller specimens, and 200 gallons (757 l) will be needed for a full sized adult. The tank should be wider and longer, rather than tall. These large tanks are needed to accommodate the amount of live rock necessary to support large quantities of naturally growing sponge and algae. Ideally the live rock is used for feeding the fish, and the aquarist provides a supplementary diet. Tanks must be very mature with lots of encrusting sponge and algae (Halimeda types) to help sustain this angelfish throughout its life. Aquarists who have been successful keeping this fish have used Florida or Caribbean live rock because these rocks are readily recognized as harboring foods.

These angelfish need several places to hide as they have a timid personality, especially when compared with others from the Holacanthus genus. Adding other angelfish is not suggested since the Rock Beauty Angelfish will stress, not eat, then get sick and may die. Obtain a specimen between 3 to 4 inches (7.6-10 cm) in length for the best success, over 4 inches is not recommended as they won’t acclimate. A pH of at least 8.0 is needed for all marine angelfish.

  • Minimum Tank Size: 100 gal (379 L) – 100 gallons (379 l) for smaller specimens and 200 gallons (757 l) for adults.
  • Suitable for Nano Tank: No
  • Live Rock Requirement: Typical Plus Hiding Places – Live rock from Florida or the Caribbean is best to provide recognizable food and juveniles need plenty of places to hide.
  • Substrate Type: Any
  • Lighting Needs: Moderate – normal lighting – Angelfish live in shallower waters and the sun helps them to produce vitamin A, so in the aquarium they need at least a daylight bulb, and the light helps natural algae to grow for their consumption.
  • Temperature: 72.0 to 82.0° F (22.2 to 27.8&deg C)
  • Specific gravity: 1.023-1.025 SG
  • Range ph: 8.0-8.4 – Angelfish need the pH to be at least 8.0 for their health.
  • Brackish: No
  • Water Movement: Any
  • Water Region: All – They will swim in all areas of the aquarium.

Social Behaviors

The Rock Beauty Angelfish is quite timidfor a Holacanthus species. Centering your tank around this angelfish is the best way to ensure a longer life, and over crowding should be avoided as they can easily become stressed. It is best kept in a system that mimics its natural environment, including fish from nativeregions.

This angelfish has been known to nip at other tank mates. One such target is a Blue Chromis Chromis cyanea. This behavior has typically labeled them as aggressive fish, but it has been discovered that this nipping is a typical response by sub-adults who have been eating the slime off of eels and other fish in the wild. Providing an Atlantic bio-type with fish from their natural habitats can help ease this behavior.

In the aquarium they become aggressive towards their own species so you should keep only one per aquarium. Do not house them with Triggers or other angelfish since they will stress this angelfish out. Also avoid sharks and stingrays as these angels have been known to nip their eyes, mistaking them for a the polyps of corals.

Opposite of what is suggested for most angelfish, the Rock Beauty Angelfish should be added to the tank first. Then after it is acclimated, eating, and calmed down you can start adding other fish. Add smaller peaceful fish first and then larger peaceful fish. These fish are not considered reef tank safe as corals will be nipped at, however invertebrates like cleaner shrimp, snails, and crabs are usually not bothered.

  • Venomous: No
  • Temperament: Semi-aggressive – The seemingly aggressive nature of nipping is due to juveniles and sub-adults feeding on the body slime of other fish.
  • Compatible with:
    • Same species – conspecifics: No
    • Peaceful fish (gobies, dartfish, assessors, fairy wrasses): Monitor – Try using fish only from their bio-type and add these after the Rock Beauty Angelfish is settled. Smaller fish should not be bothered in larger tanks.
    • Semi-Aggressive (anthias, clownfish, dwarf angels): Monitor – Make sure these fish are not harassing or stressing out the Rock Beauty.
    • Threat – These fish may be too aggressive for a young Rock Beauty.
    • Large Semi-Aggressive (tangs, large angels, large wrasses): Monitor – Do not add with other large angelfish and only very mellow tangs. An Atlantic tang would be best, however surgeonfish will compete for algae so a large tank over 250 gallons is suggested to keep this mix.
    • Large Aggressive, Predatory (lionfish, groupers, soapfish): Monitor – Slower moving sharks and stingray, especially their eyes, may be picked by larger angelfish as well as slow moving fish with appendages like lionfish. Monitor for any signs of nipping.
    • Threat
    • Anemones: Threat
    • Mushroom Anemones – Corallimorphs: Threat
    • LPS corals: Threat
    • SPS corals: Threat
    • Gorgonians, Sea Fans: Threat
    • Leather Corals: Threat
    • Soft Corals (xenias, tree corals): Threat
    • Star Polyps, Organ Pipe Coral: Threat
    • Zoanthids – Button Polyps, Sea Mats: Threat
    • Sponges, Tunicates: Threat
    • Shrimps, Crabs, Snails: Safe
    • Starfish: Monitor – May nip at appendages.
    • Feather Dusters, Bristle Worms, Flatworms: Threat
    • Clams, Scallops, Oysters: Threat
    • Copepods, Amphipods, Mini Brittle Stars: Safe – Will not eat enough of them to affect population.

Sex: Sexual differences

Males are generally larger than the females in their own harem. Males also have trailing filaments off the top part of the tail fin and the tips of both the dorsal and anal fins. The Rock Beauty will reach sexual maturity at 3.9†(10 cm) as spawning females, but mature males are 8†or larger.

Breeding / Reproduction

Breeding Rock Beauty Angelfish, to our knowledge, has not been accomplished in captivity. In the wild, the male angelfish will defend a territory with two or four females. A sub-adult female may be allowed to occupy the same area as an adult female within a harem. It is thought that if the male dies, one of the largest females will then turn male, and the smaller female will then assume a roll in the harem as a spawning female.

Spawning occurs in the evening. Pairs will spawn by slowly rising up in the water column while bringing their bellies close together, and releasing large amounts of eggs and sperm. A female can release anywhere from 25,000 to 75,000 transparent eggs each evening, and the male will fertilize them. She can spawn nightly for a few days in a row, and this can total as many as ten million eggs for the duration of the spawning cycle.

The eggs are transparent and pelagic, floating in the water column. The eggs will hatch in 15 to 20 hours. At this point the “pre-larval” angelfish is attached to a large yolk sac, has no functional fins, no eyes, or gut. After about 48 hours the yolk is absorbed during which time the fish develops into true larvae and begins to feed on plankton in the water column. Growth is rapid and 3 to 4 weeks after hatching the fish will reach about 15-20mm and will settle on the bottom of the ocean floor and start their new stage in life as a tiny Rock Beauty Angelfish.

  • Ease of Breeding: Difficult

Fish Diseases

Some common initial issues with the Rock Beauty Angelfish is the appearance of red and/or bloody marks and sores as well as acting out of sorts. Many have had success treating this with Furan medications, Nitrofurazone in particular. Use a full dose but in a separate tank, not the main system, and have plenty of aeration. Do daily water changes and then re -administer medication to keep levels at the full dose. Do not try to feed your angelfish at this time. It will result in fouling the water and typically they will not eat at this time anyhow. Some have used tetracycline and erythromycin. As with any medication, use the full dose or the illness could come back with a vengeance.

Like other saltwater angelfish they 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. Providing an angelfish with clean water, a proper decor with places to hide, and regular feeding is the best way to prevent illness. Calm angelfish are healthy fish. If not stressed, they will have a stronger immune system to prevent infections.

A condition called nutritional blindness, caused by inappropriate levels of meaty foods, can occur in angelfish around 6 to 8 months after taken into captivity. To avoid this condition feed green leafy foods that have Vitamin A, as well as making sure there is plenty of natural occurring algae in the tank. The Holacanthus genus are less prone to nutritional disorders such as Lateral Line Disease, which results from not enough vegetables with vitamin A and C.

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.

A viral infection, Lymphocystis, looks like small cauliflower-shaped nodules on the fins and mouth. These nodules are not harmful and come and go. The only time action may be needed is if they were on the mouth area of the fish, preventing it from eating for a prolonged period of time. It’s best to do water changes to help the fish’s natural immune system kick in.

Monogenetic flukes are the most common parasitic infections angelfish are prone to contracting. 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.

Fish problems can be broken into one of (or a combination of) these types: parasites, bacterial disease, fungal disease, or physical ailments caused from deficiencies in diet as well as wounds and injuries. For more information on diseases that saltwater angelfish are susceptible to, see Aquarium Fish Diseases and Treatments.


Rock Beauty Angelfish are commonly available in pet stores and online, and range in price from moderate to moderately expensive, depending on size.


 Rock beauty Holacanthus tricolor (Image Credit: Paul Asman and Jill Lenoble, Wikimedia Commons CC BY-SA 2.0 Generic)