Emperor Angelfish: Species Profile, Care, Tank Setup & More

Pomacanthus imperator - emperor angelfish - saltwater fish
Pomacanthus imperator – emperor angelfish

In any aquarium, the Emperor Angelfish is sure to be the star of the show. Many aquarists are drawn to their bright colors but quickly intimidated by their care requirements.

However, with the right knowledge and resources, caring for your fish doesn’t have to be an ordeal. In this guide, learn everything our experts have to say about how to properly care for the Emperor Angelfish.

Species Overview

Scientific NamePomacanthus Imperator
Common NamesEmperor Angelfish, Imperator Angelfish, Imperial Angelfish
Price Juveniles: $130-$200 Adults: $400-1,400
DistributionIndo-Pacific Ocean
Size~12 inches (in captivity)
ColorDark blue and bright yellow stripes, black mask around eyes, white mouth, yellow tail, black gills and pectoral fin (adult fish)
DietSpirulina, commercial marine fish food, spinach, marine algae, shrimp, scallops, squid, live & frozen food
TemperamentSemi-aggressive, territorial
Minimum tank sizeJuvenile: 125 gallons Adult: 220 gallons
Place in the tankWater Column
Care levelUpper intermediate 
BreedingNot recommended
Life expectancy20+ years

History and Background

With their bright colors and quirky personalities, this species is often a favorite of saltwater aquarium keepers and is one of the larger fish that you can keep in captivity. They have a status of as least concern according to the IUCN Red List meaning that there are a large number of them in the wild.

Scientifically known as the pomacanthus imperator, this species goes by many names such as the imperator angelfish and imperial angelfish. However, their most common name is emperor angelfish.

Origin

First documented in 1787 by Marcus Bloch, Emperor angelfish are common in tropical waters such as those found in the pacific and indian oceans, red sea, and southern Japan. They have been found in the Great Barrier Reef, Easter Islands, New Caledonia, French Polynesia, East Africa, and other areas with coral reefs.

More recently they have been found in Puerto Rico, Florida, Hawaii, and southwestern Mediterranean which is likely due to hobbyists releasing them into local waters. As they are generally not reef safe species, you will find them where many stony corals exist as they will eat at many soft coral.

Are Emperor Angelfish hard to keep?

Emperor Angelfish are generally considered more difficult to keep. This is largely due to their temperament and tank requirements. Emperor Angelfish are a semi-aggressive fish who will prey on smaller fish. They are very territorial and males should not be paired together. Furthermore, Emperor Angelfish may behave aggressively towards other angelfish with a similar pattern to them.

Emperor Angelfish also requires a large tank. An adult Emperor Angelfish should be placed in a tank no smaller than 200 gallons. This coupled with their dominant personalities can make them challenging to care for. However, with the right knowledge and resources, these fish can be a beautiful addition to your saltwater aquarium.

Appearance

Emperor Angelfish (Pomacanthus Imperator)
Emperor Angelfish (Pomacanthus Imperator)

A blue body covered with yellow stripes is sure to draw the eye of any onlooker to your community tank. One emperor angelfish can provide hours of entertainment with their beautiful long body and vibrant coloring.

What do emperor angelfish look like?

Adult Emperor Angelfish have bright yellow horizontal stripes which alternate with dark blue stripes. These stripes extend from the base of the tail to the gills. Around the eyes, they have a black mask, and the top of their face is greenish yellow. Their mouth and dorsal fin are white while both their gills and pectoral fin are black. The anal fins gradiently shift from black to blue, and their tail is yellow.

Adult coloration is drastically different from that of the juvenile. The Emperor Angelfish juvenile has a black body with concentric rings of white and sapphire blue which grow larger as they expand from the base of the tail. The fins are blue with white edges, and they have spots from the dorsal to anal fin. They have a skin flagellate along their tail.

FACT

Until the 1930’s, scientists believed the Emperor Angelfish juvenile was a completely different species from the adult due to how different they look.

Color Variations

There are some color differences between male and female emperor angelfish. Males may be bluer while females tend to be grayer. Males may also have brighter colors.

How big do emperor angelfish get?

In the wild, they can grow up to 15 inches. In captivity, they rarely get bigger than 12 inches long. Females are typically smaller than males.

When does an emperor angelfish change colors?

An emperor angelfish juvenile will start to change color as it enters the sub-adult stage. Generally, the first sign that the emperor angelfish juvenile is changing color is yellowing at the base of the tail. Within 24-30 months, it should have achieved its full adult colors.

Temperament and Tankmates

Emperor Angelfish And Yellow Tang in a Reef Tank
(1) Emperor Angelfish And Yellow Tang in a Reef Tank

The emperor angelfish size can make it a terrifying species unless housed in a larger tank. While you might think that the emperor angelfish size makes it incompatible with other fish, there are some similar species that can be housed together and provide your tank environment with a rich culture.

What fish can live with Emperor Angelfish?

Like most large angelfish, Emperor Angelfish are semi-aggressive and tend to exhibit territorial behavior. As such, tank mates should be chosen carefully. Fish that are most likely to do well in the same tank as an Emperor Angelfish will be of a similar size or slightly smaller.

Tank mates should also be aggressive or semi-aggressive. Contrary to what one might think, it is better to place several aggressive fish in one tank than to mix docile and aggressive fish. Putting many aggressive fish together makes it less likely that one fish or fish group will become the target for bullying.

To decrease the likelihood of the Emperor Angelfish bullying others, they should be introduced last to the tank. A tank that has been established for at least 6 months is the ideal environment for them. Introducing an emperor angelfish juvenile instead of an adult will also reduce the chances of aggression towards other fish in the tank.

Top 5 Compatible tank mates

1. Tangs

Tangs are too big to be considered prey by Emperor Angelfish and will flourish in the same environment. Sohal, blue, and yellow tangs are all recommended varieties.

2. Grouper

These fish can pair well with any variety of large angelfish. While not particularly aggressive, grouper are carnivorous. Be cautious of placing them with smaller fish or invertebrates.

3. Yellowtail Damselfish

Although this tropical fish rarely grows larger than 3 inches, its aggressive nature makes it suited to sharing a tank with Emperor Angelfish. They also pair well with Dottybacks.

4. Dottyback

Similar to the Yellowtail Damselfish, this tiny fish partners well with Emperor Angelfish due to its aggression. Make sure to give it caves to hide in that are too small for the Emperor Angelfish to enter.

5. Some Other Angelfish

Emperor Angelfish will behave aggressively not only towards other Emperor Angelfish but also towards any variety of angelfish with similar patterning. As such, only certain varieties– such as flame, coral beauty, and swallowtail angelfish- will make suitable tank mates.

Tank mates to avoid

Smaller fish or those who have long fins may be perceived as prey by the emperor angelfish. Clownfish, for example, do not make good tank mates. More docile, passive fish will also not pair well with the emperor angelfish.

Finally, there should be no more than one male Emperor Angelfish in an aquarium. Males will become highly territorial and prone to fighting one another. To keep more than one emperor angelfish, two females or one male and one female will pair nicely together.

Tank Requirements 

Big Empty Fish Tank on White Background
Big Empty Fish Tank on White Background

The most important aspect of emperor angelfish care is ensuring that the tank conditions are just right. Due to the emperor angelfish size and its proneness to disease it is important to have excellent water quality prior to their addition to the tank.

Tank Size

For an Emperor Angelfish juvenile, a 125 gallon tank or greater is required. For two juvenile Emperor Angelfish, required tank size increases to 180 gallons. An adult emperor angelfish will need a 220 gallon tank, and you’ll need an even bigger tank if you own two. However, these are just the minimum requirements. In the wild, an Emperor Angelfish’s territory usually ranges around 10,000 square feet, so the larger the tank, the better.

Water Parameters 

Water TypeSaltwater
Water Temperature72–82°F (22.2–27.7°C)
Water pH8.1-8.4
Water Hardness8-12 dKH
SubstrateAny
Tank setupLive rocks, caves, plants, well-lit, corals (food source; optional)
FilterYes, necessary
PumpNo
Water HeaterYes
LightingStrong
Reef SafeNo

Are Emperor Angelfish Reef Safe?

No, they will eat invertebrates as well as both hard and soft corals. Anemones, clams, and zoanthids are all likely to be nipped at. While not guaranteed, small polyp stony corals may be ignored by your fish if it is well fed. Similarly, small polyps, bubble corals, hammer corals, and star polyps may do well.

Plants

Almost any tropical, saltwater plant it can behind will be loved by your emperor angelfish. Turtle grass shoots, mermaid’s fan, green finger plant, halimeda, and dragon’s tongue algae are all recommended.

Filter

Emperor Angelfish produces a lot of waste. A strong filtration system is necessary to prevent ammonia spikes.

Pump

Slow-moving water is preferred by these fish as it mimics their natural habitat. So, a pump won’t be necessary.

Heater

Emperor Angelfish are tropical fish who require warmer waters to survive. A heater is recommended. The emperor angelfish prefers water that is 72–82°F.

Substrate

These fish aren’t picky about substrate, and you could choose any. One important factor to keep in mind is that some fish will occasionally swallow rocks off the bottom of the tank. To prevent complications from this, it’s recommended you choose a substrate either larger than your fish’s head or small enough that it could easily pass through their system.

Lighting

Emperor Angelfish prefer an aquarium environment that mimics their natural habitat as closely as possible. Bright lighting is best for keeping these fish happy.

Diet and Health

Bloodworms in Plastic Container
Bloodworms in Plastic Container

When you first introduce your emperor angelfish to the tank they will likely be too stressed out to eat. You should add live rock prior to introducing them to provide them with supplemental food that they can nibble at until they feel comfortable in the aquarium, this will likely take a few weeks.

TIP

If you are having trouble getting your angelfish to eat, provide it with a few clam mantles.

What do emperor angelfish eat?

Emperor Angelfish are omnivores who enjoy a variety of foods. In the wild emperor angelfish are well known as cleaner fish who eat bits of algae, meat, seaweed, small crustaceans, and sessile invertebrates like sponges.

In captivity you should feed your angelfish a variety of high quality foods to keep your fish happy. While you can feed your fish commercially available marine food pellets you’ll want to supplement their diet with frozen foods such as brine shrimp, squid, and bloodworms, as well as fresh greens such as spinach, and spirulina.

Other foods include:

  • Clams
  • Scallops
  • Marine Algae
  • Sponge (Porifera)
  • Dried Corals
  • Shrimp

If you decide to feed your fish commercial pellets or flakes be sure that they contain small portions of spirulina or sponge, as these are important for a complete diet. Also be aware that flakes and pellets will expire and that their nutrients will diminish over time.

TIP

Diet plays a crucial role in adult fish fully developing their color. Make sure to feed them properly to ensure their trademark look appears.

When to feed an emperor angelfish?

You should feed your emperor angelfish once a day for 5 minutes. 

How much to feed an emperor angelfish?

You should give your emperor angelfish as much as they can eat during their 5 minute feeding session. If you have more than one fish in your tank you should distribute food evenly throughout the water column to ensure that all fish have enough food. If you feel like there is not enough food available, you can supplement their diet with the addition of a live rock to their tank.

How much food do I feed my juvenile emperor angelfish?

Depending on how young your emperor angelfish juvenile is, you should offer it a diet that is the size of their mouth. Newly free-swimming fry should be fed a diet of microworms and infusoria. At 3-4 weeks old, you can begin feeding crushed marine flakes and baby brine shrimp. At 4-6 weeks, you can begin feeding the juvenile the same diet as an adult.

Since an emperor angelfish juvenile will expend more energy throughout the day, you should feed them in smaller, more frequent increments than the adults. Feeding sessions should occur 2 to 3 times a day for 3 minutes each.

Common diseases of emperor angelfish

Emperor angelfish are very susceptible to diseases including ich, marine velvet, head and lateral line disease, lateral line erosion disease, and parasitic infections. We’ve listed the more unusual disease symptoms, causes, and treatments below. 

Head and lateral line disease

Also called the hole in head disease it can be identified by small dark holes or divots around the head or along the lateral line and is caused by long term stress weakening the immune system. Treatment includes identifying and eliminating the stressor.

Marine Velvet

Caused by a dinoflagellate parasitic infection and presenting as dusty brown and gold colored spots. If left untreated velvet can cause serious health issues leading to hypoxia or the dying of gill tissues. Treatment includes copper sulfate, methylene blue, or formalin baths as well as quarantining infected fish.

Emperor Angelfish lifespan

If you’re planning to add Emperor Angelfish to your home aquarium, be prepared to have them for a while. When raised in captivity, they can live for over 20 years! 

Breeding

Emperor Angelfish and Cleaner Wrasse
Emperor Angelfish and Cleaner Wrasse

Because of their size and temperament, it is already tricky enough to provide care for one imperator angelfish! Attempting to breed them on top of this can prove to be quite difficult. 

Can you breed Emperor Angelfish?

For most home aquarists, breeding Emperor Angelfish is not recommended. Unlike breeding freshwater angelfish, Emperor Angelfish require a large space to breed; much larger than most home aquariums can provide.

How to breed emperor angelfish?

There are no known successful examples of breeding Emperor Angelfish in captivity. In the wild, Emperor Angelfish typically spawn only once per year. During a short window in late Autumn/early Winter, they will rise to the surface of the water in pairs to fertilize the eggs. The female will then release the eggs into a strong current causing them to scatter. Without sufficient space and just the right conditions, Emperor Angelfish will not even attempt breeding.

Is the emperor angelfish for you?

While these brightly colored fish are sure to attract the attention of many aquarists, they do require a bit of care. Before purchasing, ask yourself the following questions.

  1. Can you provide this fish with the appropriate tank size (220 gallons) and necessary tank conditions?
  2. Do you own a community tank that is already well-established and will allow for adequate swimming space?
  3. Are the fish in this tank well-suited to being paired with an Emperor Angelfish?

If you answered yes to all of the questions above then an Emperor Angelfish may be right for you! With diligent care and high quality angelfish preparations, Emperor Angelfish (pomacanthus imperator) can be an excellent addition to your saltwater tank.

If not, a beginner saltwater fish species such as the Royal Gramma Basslet might be a better choice.

Conclusion

The Pomacanthus imperator can be an intimidating species, but after our emperor angelfish care guide we hope you no longer find the emperor angelfish size, temperament, or maintenance aspects to be quite as terrifying.

(1) Rudolphous, CC BY-SA 4.0, via Wikimedia Commons

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