Emperor Angelfish: The Complete Care Guide

The Emperor Angelfish is perhaps the most recognizable angelfish in the aquarium trade. It is both graceful and vibrantly colored and is often the crowning jewel of the aquarium.

Although they are fairly hardy, they should only be kept by experienced fish keepers due to the tank size requirements, and strict water parameters.

Whilst this fish is well recognized and very popular it does come with a relatively high price tag.

In this complete care guide we will detail their tank requirements and dietary needs before discussing how to spot a healthy Emperor Angelfish and whether they can be kept with other fish.

Category Rating
 Care Level: Moderate
 Temperament: Semi-Aggressive
 Color Form: Yellow, Blue
 Lifespan: 20+ Years
 Size: Up to 12″
 Diet: Omnivores
 Family: Pomacanthidae
 Minimum Tank Size: 125 Gallons
 Tank Set-Up: Marine: Rocks and Certain Coral
 Reef Compatible (Safe): Varies

Emperor Angelfish Overview

The Emperor Angelfish is one of the most striking and beautiful saltwater fish around.

Also known as the Imperator Angelfish and the Imperial Angelfish, it is part of the Pomacanthidae family and is commonly found in the Indo Pacific Ocean.

Emperor AngelfishIt was first identified in 1787, and given the scientific name of Pomacanthus Imperator.

The Imperial Angelfish can have a lifespan of over 20 years in captivity, and even longer in the wild. They are moderately difficult to keep due to the level of water quality in which they need to thrive, and the size of the tank needed.

They are a very popular and readily available fish, but come with a high price tag due to their desirability.

Appearance of Emperor Angelfish

Adult Emperor Angelfish
Adult Emperor Angelfish

The Emperor Angelfish transforms through three different stages (juvenile, sub-adult and adult). In each stage its appearance drastically changes.

The juveniles and the adults both have strikingly different colorations and patterns.

In fact, up until 1933 the juvenile was thought to be a different species called the Pomacanthus Nicobariensis.

Juvenile Emperor Angelfish have a black body with light blue and white vertical lines on their face. Their body is made up of three wide white curved bands. The first runs from the dorsal fin to the anal fin, the second creates a ‘C’ shape and the third is a white circle close to the tail fin.

In between each of the thick white curves are thinner light blue curves. The dorsal and anal fins are made up of black hexagonal markings with light blue trimming.  The dorsal fin also has a white edging.

Juvenile Emperor Angelfish
Juvenile Emperor Angelfish

The sub-adult is similar in appearance to the juvenile, but you’ll notice the tail fin starts to develop a yellow patterning, as well as yellow vertical lines on the body. Their body will also become deeper and rounder.

Once fully developed, the adult is deep bodied with yellow and blue striped lines which stretch horizontally across their body from the gill area to the start of the yellow tail fin.

The dorsal fin has a white edging. It has a mask-like black band across its eyes, which has a blue trim. The mouth and snout are white. These changes usually occur over a period of around 2 years, when the fish is 3-5” in length. The color change is often delayed in captivity.

In the wild, Emperor Angelfish can grow up to lengths of 40cm (15”) however in aquariums they’re much less likely to reach these lengths.

Instead, you can expect this species to reach around 12” (30cm) in captivity.

This fish can be mistaken for the juvenile Koran Angelfish (Pomacanthus Semicirculatus). The difference lies in the last white strip, which makes a C shape rather than a circle shape.

The Koran also doesn’t have the honeycomb patterning on the dorsal and anal fin.

Emperor Angelfish Habitat and Tank Requirements

Emperor Angelfish ThreeNatural Habitat

Emperor Angelfish inhabit reef areas of the Indo-Pacific Ocean.

Juveniles live alone and are mostly found hiding out in rockwork around the outer edges of the reef whereas sub-adults venture further out to reef’s front holes surge channels. Both juveniles and sub-adults act as cleaner fish. Adults can be found in channels, seaward reefs and areas of rich coral growth in clear lagoons.

Males are territorial and have a large territory (as large as 10,000 square feet) which they share with two or more females.

Tank Conditions

It’s always important to try and transfer a species natural environment into the tank, so to replicate this, they require a minimum tank size of 125 gallons for a juvenile and at least 180 gallons for a pair.

Include plenty of live rock for the fish to graze on, and the rock will also double as hiding areas which help to make it feel secure. As well as hiding areas, they also require plenty of open swimming space.

The tank should be kept in between 72-82oF (22.2-27.8oC) with a pH of 8.1-8.4 and a specific gravity of 1.023-1.025.

They can tolerate most types of water movement, but prefer slow-moving water.

Many aquarists complain that captive Emperor Angelfish are never as brightly colored as their wild counterparts, however providing plenty of light (as you would for reef tanks) may help. Lighting also helps to prevent Head and Lateral Line Erosion Disease. This species is prone to disease, so maintaining high quality water conditions is essential.

Emperor Angelfish require such a large tank because they need plenty of regular feeds which creates a large bio-load on the aquarium. You tank should be fully cycled and ideally should have been set up for a minimum of 6 months before you introduce any Angelfish to it.

You’ll also want to keep your water in optimal condition by performing regular water changes.

By performing plenty of water tests on your tank, you’ll be able to keep on top of your water conditions and pick up changes quickly in order to correct them. You should change 15% of the water every two weeks, or 30% every month. If your tank has corals in it, remove slightly less water; 20% per month, 10% every two weeks, or 5% a week.

Although in the wild, this species lives amongst corals, it can be tricky to keep captive angelfish with corals, because they tend to nip at most stony and soft corals.

However they can be kept with most small-polyped stony corals (SPS corals) hammer corals, bubble corals, star polyps and disc anemones.

Emperor Angelfish Food and Diet

Depending on the age of the fish, you might find that they refuse food when they are first introduced. This is why an established tank is preferable – so they can find their own food whilst they acclimatize.

In the first couple of weeks it is best to feed them little and often, up to 5 times per day.

Emperor Angelfish are omnivores, meaning they eat both meat and plant matter; they will need a balanced diet of vegetable matter, meaty foods and sponge material.

It is very difficult to replicate the diet they have in the wild, because they eat a wide variety of sponges, small organisms such as tunicates, hydroids and bryozoans, and small amounts of algae.

To keep replenishing your tank with enough sponges would be difficult and expensive.

Therefore you should feed your angelfish a diet of Spirulina, algae, plenty of live or frozen foods and formula foods. They will accept vegetable based foods and meaty foods such as chopped squid, scallop and shrimp. You might also want to make your own food at home to ensure they get the best possible diet. This can consist of mussels, shrimp, squid and spinach.

Once they have acclimatized to tank life, you should feed your angelfish small amounts, two to three times a day. Remember to remove any food they haven’t eaten after 5 minutes to keep the water quality optimal.

Compatibility with other Fish

Emperor CompatibilityEmperor Angelfish are semi-aggressive, and can be aggressive to other angelfish of a similar shape. It is possible to keep other Angelfish with the Emperor, as long as they are not too similar visually.

Always introduce a juvenile Emperor Angelfish as the last fish to the tank; this should prevent any territorial behavior. Small peaceful fish are likely to be harassed by this species. They get on well with most other large saltwater fish that are not similar in shape.

You should also avoid any fish which are small enough for them to eat.

This species may initially be shy when you first introduce them to the aquarium, but in general become a very active fish.

You might also find that your Emperor Angelfish makes a grunting noise when it feels threatened.

Choosing your Emperor Angelfish

Emperor Angelfish do not ship well and are prone to stress so it’s important you choose a fish which is healthy.

Ideally when you choose an Emperor Angelfish, you should buy a juvenile that is around 4-6” as they find it easier to adapt to captivity. Make sure they are active and curious about their environment.

Check their gill count; if it’s over 80 a minute and they are swimming calmly, take this as a red flag. If the fish appear overly bright and disorientated, they might have been treated with cyanide – again another red flag.

You may find that the colors aren’t as bright as wild emperor angelfish, you can use color enhancers in their food to improve their color.

Is the Emperor Angelfish Right For Your Aquarium? (Summary)

If you’re looking for a vibrant and beautifully patterned fish for your saltwater aquarium, the Emperor Angelfish would make a perfect addition.

You’ll need to be experienced in keeping saltwater fish, and this species is one of the less forgiving ones with regards to water conditions.

You should keep your water conditions pristine, and be able to house them in a large tank.

Given their semi-aggressive nature, you should try to make sure they are the last you add to your tank. To achieve this, you can write a wish list of fish to ensure they are all compatible and added in the correct order.

Are you thinking of getting an Emperor Angelfish, or do you already have one? We’d love to hear from you, so leave us a comment below…

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