Emperor Angelfish (Pomacanthus Imperator)

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Last updated on September 7th, 2022 at 05:35 am

The emperor angelfish (Pomacanthus imperator) is a saltwater fish of the family Pomacanthidae, found in the Indian and Pacific Oceans. It was first named by Kuhl in 1820. They grow to around 15 inches in length and are deep-bodied, with males being darker than females, and have nine dorsal spines, with the second shortest; they also have 2 anal spines, 25 to 26 dorsal soft rays, and 20 to 21 anal soft rays.

Plenty of fish get the label ‘angel’ in their names, but only one earned it in its scientific name: the emperor angelfish (Pomacanthus imperator). Although this aptly named fish isn’t actually an angel at all, it belongs to the family Pomacanthidae, so it’s an angelfish, it’s certainly regal enough to deserve the moniker.

Pomacanthus imperator is one of the largest angelfish and one of the most beautiful saltwater fish you can add to your home aquarium. Angelfish are also easy to keep, making them a good choice if you’re new to the world of saltwater aquariums or have only kept freshwater fish before.

There are many fish species in the marine aquarium hobby, and the Pomacanthus imperator (commonly known as the emperor angelfish) is one of the most popular choices among hobbyists due to its attractive coloration and large size (up to 20 inches). But what else should you know about this beautiful fish?

If you’re thinking about adding an emperor angelfish to your tank, here’s what you need to know about its care requirements, feeding habits, and more.

Origin and description

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Pomacanthus imperator is a marine angelfish belonging to the family Pomacanthidae. It was described by Linnaeus in 1758. Its specific epithet imperator literally means emperor in Latin, as an adjective referring to its coloration and patterning when young; it is sometimes called emperor angelfish for its appearance. Emperor angelfish are native to reefs in the Indian Ocean and the western Pacific Ocean.

They are generally found at depths from 10 m to 60 m, though they can be found down to 120 m. Adults may grow up to 15 inches long, with a maximum length of about 20 inches. The body is deep blue-green or dark green with white spots on its body and fins.

Silver Pomfret Fish (Pampus argenteus)

Species profile

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The emperor angelfish is a stunning, rainbow-colored saltwater fish native to coral reefs in tropical oceans. It grows up to 20 inches in length and can live more than 10 years in captivity. Also known as Pomacanthus imperator, it’s one of seven types of angelfish common throughout coastal regions.

Juveniles have spots that fade as they mature. Males sport red and blue vertical stripes. Females are blue with white streaks. Both sexes can be aggressive when mating or protecting territory; care must be taken when housing them together or with other similarly sized species. Emperor angelfish enjoy an omnivorous diet consisting of aquarium plants, invertebrates, and meaty foods such as frozen brine shrimp, marine pellet food, or fresh seafood such as mussels or scallops.

Scientific name

The scientific name of the emperor angelfish is Pomacanthus imperator

Pomacanthus imperator habitat

The emperor angelfish is a marine angelfish and can only be found in saltwater. It lives in saltwater at a depth range of 0 to 50 meters. It has several natural predators including groupers, sharks, moray eels, and snappers. However, it is large enough to avoid its predators most of the time.

Emperor angelfish size

Emperor angelfish grow to about 15 inches long and are typically aquascaped with live rock.

Emperor angelfish tank size

Emperor angelfish are active swimmers and should be kept in tanks that have plenty of room for them to swim around freely. These fish get quite large, so you’ll need a tank with a minimum volume of 200 gallons. Since these fish like to hide at times, provide them with plenty of rockwork or other places where they can burrow if they want some ‘alone time’.

Pomacanthus imperator tank set up

To succeed with emperor angelfish, you need to set up a large, highly decorated aquarium of at least 200 gallons. You can expect your fish to grow to 6 or 7 inches and live for 20 years or more. In such a large tank, you’ll have plenty of room for lots of plants, driftwood, and other decorations.  Because these fish are so territorial, it is best to keep only one male per tank. If there are multiple males in one tank, they will fight incessantly; eventually, one male will kill all others in his territory.

Paracentropyge Multifasciata (Multibar Angelfish)

Emperor angelfish tank mates

While Pomacanthus imperator can be housed with other non-aggressive species, it’s best to avoid housing them with smaller fish because they have a voracious appetite and may consume their tank mates without realizing it.

Some good tank mates are lionfish, dottybacks, rainbow fish, wrasses, damselfish, and other large angelfish. Emperor angelfish also get along well with triggerfish and clownfish.

Pomacanthus imperator breeding

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The Emperor Angelfish is one of several marine fish which can be bred in captivity and is one of two angelfish species used by aquarists. It lives in holes and crevices in coral reefs. The female lays her eggs on a flat surface above the water, usually a rock or plate, and attaches them to any solid object using strands of mucus from her abdomen. She will then guard them until they hatch after 6 days.

The male keeps close watch over his family, chasing away intruders such as butterflyfishes while they develop. He continues to protect them even after hatching and continues to keep them together for an additional five weeks, during which time he also shelters them in his territory. In order for spawning to occur, both parents must be well fed.

Pomacanthus imperator will accept most foods offered such as live brine shrimp or flake food with vitamins but are fussy eaters requiring frequent partial changes of water during the breeding season. Their captive diet should consist mostly of vitamin-enriched frozen Mysis shrimp.

Occasionally, live chopped amphipods may be accepted by large adults after conditioning over a period of several months; to offer these, it may be necessary to lower their pH level and raise their temperature somewhat. After feeding has been completed, reduce feeding levels and raise the temperature again gradually in preparation for spawning.

Are Emperor angelfish aggressive or peaceful?

Pomacanthus imperator is highly territorial and will act aggressively towards any fish that encroach on their territory. You’ll need a large tank to house them, as they tend to be rather aggressive when they reach maturity. If you have other fish in your aquarium, emperor angelfish will bully them.

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Emperor angelfish care

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The Pomacanthus imperator is one of several beautiful varieties of angelfish kept in captivity. This species hails from coral reefs located throughout eastern Indonesia, Papua New Guinea, and northern Australia. They can grow to be anywhere from 15 to 20 inches long when fully mature but are much smaller when they first start out.

A young Pomacanthus imperator will generally stay in its home reef for a few years before moving on to another location to live on its own and establish its own territory. You’ll want to make sure you keep your emperor in an aquarium that is at least 180 gallons or larger.

Their natural environment has very little current and clear waters, so it’s best if you give them something along those lines so they don’t get used to swimming in areas with fast currents or cloudy water. In addition, you should add plenty of rocks and caves around your aquarium since emperors love to hide among their surroundings while they sleep.

What Emperor angelfish eat

Emperor angelfish are omnivores, meaning they eat both plant and animal matter. In their natural habitat, they feed on crustaceans, mollusks, and algae. In captivity, they can be fed high-quality marine flake food every day or two. Make sure it has a lot of protein in it and very little fat; also try to avoid foods with lots of additives like sugars or vitamins.

You should also supplement their diet with vegetable matter – I recommend frozen mixed veggies such as broccoli and peas. Feed these once a week only, you don’t want them getting used to eating veggies daily!

Light requirements/Water flow

While Pomacanthus imperator isn’t particularly fussy about lighting or water movement, one important thing you need to remember is that they don’t tolerate low levels of dissolved oxygen well at all.

Water parameters

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The temperature should be between 70 and 78 degrees Fahrenheit (25 – 27 degrees Celsius), pH of 8.1 – 8.4, Specific Gravity of 1.020 – 1.025, Alkalinity of 2 to 3 dKH or 4 to 7 ppm, Calcium: 400 to 430 ppm, and Magnesium: 1350 to 1500 ppm, but can be adjusted based on your fish and tank size by adding calcium carbonate powder or calcium chloride solution under 15mg/L respectively.

Blue Chromis Fish Care (Chromis Cyanea)

I personally prefer 5mL of baking soda per 10 gallons of water to raise my alkalinity slightly as it will buffer pH for me so I don’t have to adjust it with chemicals unless it changes drastically. It also brings up my calcium level a little bit, however, if you start seeing small deposits on items in your tank from your tap water then you might want to try 5mL of vinegar per 10 gallons instead, which will decrease alkalinity without affecting hardness levels.

Emperor angelfish lifespan

The emperor angelfish is a very durable fish that can live up to 20 years in captivity.

Parasites and diseases

The most common external parasite affecting pomacanthus imperator is Cryptocaryon irritans, or marine ich. This is usually treated with copper-based medications. Internal parasites are also a problem in emperors. These include flukes of several varieties, protozoa, and worm infestations. Diseases that affect tank mates can also impact these fish, but keeping them healthy reduces their susceptibility to many infections and diseases.


The pomacanthus imperator most common and primary predators are larger predatory fish such as barracuda and grouper. Large angelfish with long jaws are capable of catching smaller fish, so they are usually not suitable for a community tank. It is recommended to place an angelfish in a large tank alone or in a pair rather than with other fish.

Do pomacanthus imperator make good pets?

No, pomacanthus imperator are not recommended for a home aquarium due to their large size and potential aggression. In addition, they need large tanks and high-quality food, meaning their care is expensive. They are better suited for a public aquarium or an experienced hobbyist’s tank.