Emperor Angelfish For Beginners (The Complete Care Sheet)

The Emperor Angelfish is one of the most popular marine fish.

Their captivating appearance will draw you in and will no doubt be the spotlight of your aquarium, dazzling visitors and thrilling family and friends.

However, you should be aware that this fish is not an easy one to keep.

They are fussy with their water parameters and even fussier with their tank mates.

Keep reading to learn all there is to know about the Emperor Angelfish, including their tank set-up, diet, tank mates and much more…

Emperor Angelfish 101

Pomacanthus imperator

The Emperor Angelfish (Pomacanthus imperator) is a beautiful saltwater fish.

They are from the Perciformes order and a member of the Pomacanthidae family, which includes all Angelfish. This family has seven genera with around 86 species of Angelfish, with some well-known species being the Royal Angelfish (Pygoplites diacanthus) and the French Angelfish (Pomacanthus paru).

This reef-dwelling fish is commonly found in the Indian and Pacific oceans. Their range extends from the Red Sea to Hawaii and the Austral Islands. Here, they can be found in the upper 100m of the reef.

Emperor Angelfish are very popular because of their beautiful appearance.

However, they are a difficult fish to take care of because of their very specific care needs. It is recommended that only advanced fish keepers keep them. They are very territorial and can be aggressive towards other fish.

On average they will live for around 20 years.

They are also very expensive:

  • Juveniles: $150-$200
  • Adults: $400-$1,400

Key Facts:

  • Experience Required: Advanced.
  • Nicknames: Imperial Angelfish, Imperator Angelfish.
  • Color Forms: Blue and yellow.
  • Size: 12-15 inches.
  • Tank Size: Minimum 220 gallon.
  • Tank Temperature: 72°F to 82°F.

  • Absolutely stunning
  • Very active and fun personality
  • Reef compatible will small polyp stony corals

  • Territorial and aggressive
  • Expensive to buy
  • Cannot be bred in captivity
  • Requires very specific water parameters

Care Guide

Emperor Angelfish

The Emperor Angelfish requires a more experienced fish keeper to take care of them.

They need a large, established tank with specific water parameters that need to be carefully monitored and maintained. You should change the water by 10% at least once every week, whilst cleaning the glass of any algae and siphoning the substrate.

This will reduce any excess nutrients and fish waste.

With reef tanks and the sensitive Emperor, you will need to use water test kits every time you do a water change to carefully monitor the water parameters. Also keep in mind that too much siphoning can reduce the number of beneficial microorganisms in the tank, so only do half of the tank at any one time.

Although emperors are hardy, they are still susceptible to these three common diseases:

  1. Ich (White Spot Disease): This is an infamous disease caused by external parasites. It is typically brought into the tank via food sources or new fish. To prevent this, you should keep on top of tank maintenance and quarantine any new fish before adding them to the tank. Ich is highly contagious and can be fatal if left untreated; luckily there is over-the-counter medication to treat it.
  2. Marine Velvet: This is another parasitic disease. You will know if your fish has marine velvet if you can see gold-covered spots on your fish’s body. Copper is an effective treatment for marine velvet.
  3. Head and Lateral Line Erosion: This disease impacts the lateral line organ and skin on the fish’s head. You will notice erosive lesions in these areas. This disease is thought to be due to nutrient deficiencies, activated carbon, parasites and carbon dust. It can be treated with anti-parasitic medication and tank maintenance.


In the wild Emperor Angelfish eat pretty much anything.

They are lovingly known as janitor fish because they eat lots of plants and small invertebrates.

You will need to replicate their omnivorous diet to keep them healthy. A rich diet is important for these fish as it will help to maintain their color and also keep them healthy.

Here are some great foods to feed your fish:

  • Marine Algae
  • Shrimp
  • Brine shrimp
  • Squid
  • Scallops
  • Spinach
  • Sponge
  • Flake and pellets
  • Corals
  • Dried seaweed
  • Spirulina

When you first introduce them to your tank they may be reluctant to eat.

Do not worry if this happens with yours. Initially offer them food 5 times a day at regular intervals. Once they are completely comfortable, lower the portions to 2-3 times a day.

The key here is to transition slowly. It is much easier to adjust juveniles to home food than adults as you feed them dry and frozen food from an early stage of their life. Adult emperors have a harder time adjusting and changing their food habits, so keep this in mind when buying your emperor.

It is also worth knowing that they can become aggressive towards other fish if there is not enough food.

Make sure everyone is getting enough food. You also want to make sure you are not overfeeding them as this can contribute to poor water quality. You can make sure this does not happen by removing any uneaten food and only providing as much food as they can eat in two minutes.


When you first get your Emperor Angelfish they can be quite shy.

You will often find them hiding more than swimming.

Your Emperor will eventually acclimate to the new environment and will become very active, exploring all regions of the tank and scavenging for leftover food. This acclimation is a good sign that your fish is comfortable. They will start to hold their ground and be aggressive towards some other species.

Signs of aggression are normal.

They will make a grunting noise or some clicking sounds when they feel threatened . This is nothing to worry about as they are more than capable of holding their ground.

Is The Emperor Angelfish Fish Reef Safe?


The Emperor Angelfish is not reef safe.

Emperor Angelfish Swimming

Habitat and Aquarium Set Up

In the wild Emperor Angelfish live in warm coral reefs in East Africa and the Central Pacific.

They often establish up to 10,000 square feet of territory, whilst living amongst plenty of coral in bright light conditions and slow-moving water.

These Angelfish usually live alone, in pairs or in harems.

In an aquarium the idea water parameters are:

Tank Parameter Requirement
Minimum Tank Size 220 Gallons
Tank Type Saltwater Coral
Temperature 72-82°F
pH 8.1
Hardness 8-12 dGH
Gravity 1.020-1.025
Flow Light
Substrate Sand or gravel

The most important thing is the tank size.

In the wild Emperor Angelfish can establish territories up to 10,000 square feet. Although it is impossible to replicate this in your home, the bigger the tank the better. A juvenile should initially be kept in a 125-gallon tank. Fully grown Emperor Angelfish should be provided at least 220-gallons as a minimum.

These fish are particular about their water conditions and will not tolerate much change in parameters.

You will need a powerful filtration system as Emperors produce a lot of waste.

Live rock is essential, as it provides a food source for your fish by establishing a large surface area for algae and other food sources to grow on. Live rock also supplies nitrifying Bacteria which help to break down organic waste. You should place live rock in areas that will maximize swimming space.

If you have an idea of where you want your corals you can also plan your live rock layout according to that. Emperor Angelfish love to nibble on coral, so choosing the right coral is important.

You should avoid soft and stony corals and opt for small-polyp stony (SPS) corals instead. Some good options include:

  • Disc Anemones
  • Star Polyps
  • Bubble Corals

In addition to coral, you can use saltwater plants for hiding spaces and for food. Here are some good options:

  • Turtle Grass Shoots
  • Mermaid’s Fan
  • Green Finger Plant
  • Dragon’s Tongue Algae
  • Halimeda

Lastly, it is important to properly cycle any tank before introducing your Emperor Angelfish. Your tank should be cycled for up to 6 months before you introduce your fish, allowing biological growth and stabilized conditions.

What Size Aquarium Do Emperor Angelfish Need?

It is very important that you provide a large tank for your Emperor Angelfish.

Each specimen will need at least a 220 gallon tank for lots of swimming.

Emperor Angelfish Appearance

The Emperor Angelfish is without a doubt one of the most magnificent reef fish.

They also go through one of the most dramatic physical changes seen among reef fish as they grow.

Juveniles are so different in appearance that scientists initially believed it was an entirely different species. Juveniles have a blue and black body adorned with C-shaped white lines resulting in a hypnotic pattern. It takes about 2 years for them to grow out of these colors and it is usually when they are between 3-5 inches long.

Adult Emperor Angelfish are truly spectacular.

They reach up to 15 inches long and have a flattened, elongated body with blue and yellow horizontal bands that alternate down their body like a ladder. They have a bright yellow caudal fin and a striking white mouth. This is contrasted with black bands that run horizontally over their eyes as if they were a raccoon.

The underside of the fish is a regal blue beginning just below the caudal fin and running the length of their body. It merges into a darker blue-black that reaches past the gills, pectoral fins and finishes just above their eyes.

Their fins are rounded and blend in with the stripes on their body.

Telling the difference between a male and female Emperor Angelfish is difficult.

If you want to sex them you will have to look for differences in color. The males are typically brighter than the females and their face is slightly bluer, whilst the females are a little less vibrant with a gray face.


There are no color varieties for this fish.

You will only find the Emperor Angelfish in a striking blue-yellow ladder pattern.

Even the males and females do not differ much in color. The only exception is the stark difference in color between the juveniles and adults.

Tank Mates

In the wild you will find the Emperor Angelfish with hundreds of different coral reef species.

However, because of the limited space in home aquariums it is challenging to pick the right tank mates. Here are some good tank mates to consider:

  • Dottybacks
  • Damselfish
  • Tangs
  • Pufferfish
  • Large Wrasses
  • Butterflyfish
  • Lionfish
  • Flame Angelfish
  • Swallowtail Angelfish
  • Groupers
  • Six-line Wrasse
  • 8-line Wrasse

It is best to introduce your Emperor Angelfish after having added these fish to your tank.

This will help to make sure that the water parameters won’t spike too much. It will also help to reduce your Emperor’s territorial behavior.

As a general rule, the more space there is the less territorial aggression you will see from your Angelfish.

There are also plenty of non-fish inhabitants you can add to your tank such as Starfish, Brittle Stars and Rabbit Snails.

You should avoid keeping these Angelfish with smaller and peaceful fish as they will be eaten. So that means Royal Grammas are out.

Also, make sure to avoid keeping them with any visually similar fish as this will cause aggression. Here are some fish to avoid:

  • Gobies
  • Fairy Wrasses
  • Pipefish
  • Mandarins
  • Clownfish
  • Dwarf Angels
  • Seahorses

Emperor Angelfish Harem

You should only keep a single male Emperor Angelfish in the tank. Two males will lead to lots of aggression and fights as they will struggle to establish their own territory.

The safest way to keep these fish together is in a harem.

This is where you get multiple females for a single male. Just keep in mind that with multiple Emperors you will need a very large tank (500+ gallons).


The Emperor Angelfish cannot be bred in captivity.

This is because they need a huge open space and very specific conditions.

In the wild mating happens over several days and typically only occurs after sunset. Throughout the day the male will swim between the females, and 30 minutes prior to spawning this activity will increase drastically.

As the male swims alongside the female, she will dictate the male’s courtship behavior by deciding the direction of movement. The male and female will continue in this way for a few hundred meters until they return to the place that they initially made contact.

They will both stop and continue their displays for 1-4 minutes before the male suddenly leaves, swimming quickly along the reef towards another female. The first female remains in the area that the male left, intermittently picking at the substrate before the male reappears after 5-20 minutes.

Vigorous courtship will now begin.

After some fluttering displays the male will position himself below the female, with his snout next to her abdomen when she ascends. There are typically a few false starts here, where the pair will begin to ascend before dropping back down to the substrate. The final, successful ascent (3-9m) results in spawning, where both the male and female will release their gametes in a cloud of white.

Unfortunately there have been no reports of successful mating in home aquariums.

Species Summary Table

Emperor Angelfish
Other Common Names: Imperial Angelfish, Imperator Angelfish
Scientific Name: Pomacanthus imperator
Family Name: Pomacanthidae
Distribution: Indian and Pacific Ocean
Size: 12-15 inches
Color: Blue and yellow
Care Level: Advanced
Temperament: Aggressive
Lifespan: 20 years
Minimum Tank Size: 220 gallons
Tank Mate Compatibility: Limited

Should You Keep The Emperor Angelfish? (Summary)

The Emperor Angelfish is sure to present a challenge for most fish keepers around the world.

They were first described taxonomically by Bloch in 1787 under the name Chaetodon imperator. Since then this taxonomy has been revised numerous times until scientists finally accepted the name Pomacanthus imperator later in 1787.

Since then they have captivated fish keepers.

You should remember that they can be very territorial, particularly around other male angelfish. It can also be difficult for them to adapt to living in a tank.

However, if you can get the conditions right then it is well worth the difficulties.

You will be rewarded with one of the most beautiful fish around.

Do you have a territorial Emperor Angelfish? Let us know in the comments section below….