| Scientific Name | Pomacanthus imperator |
| Difficulty | Medium |
| Final Tank Size | 200+ Gallons |
| Diet | Omnivore |
| Water Parameters | 72-78 F, pH 8-8.4, Salinity 1.020-1.025 |
| Aggression | Semi-aggressive |
| Size | 15" |
Their body is somewhat elongated. Combine this with their stock build and they cannot turn quite as quickly as other fish. This makes them have a more flashy appearance when they turn around. As they are fairly dominant and territorial you can expect them to flair their fins and spines frequently without harming any fish in the aquarium. They enjoy spending their time around the rocks of the tank, looking to graze throughout the day on any algae, sponges or LPS corals.
The get quite big, often over 15 inches in the wild, but usually staying under 14 in the aquarium. They should not be kept in tanks under 200 gallons unless you are planning to move them to bigger tanks as they grow. Keeping them in smaller tanks that they can survive in will stress them out, increasing aggression and the risk for illness. They are not exceptionally tall like some other angels and are quite maneuverable. This allows you to keep a large amount of rock with caverns, over hands and cave systems that smaller fish enjoy. Those that are big enough for the Emperor Angelfish to swim through are likely to be used frequently. Despite their dominance they enjoy hiding in the rocks and watching other fish swim by. Overall they have a lot of different moods/behaviors and are interesting to watch throughout the day.
Is the Emperor Angelfish Reef Safe?
They are not reef safe fish. They will eat just about any LPS, large polyp stony coral, as well as clams, oysters and sponges. Some aquarists will have success in keeping them with clams but the clam will always be at risk of nipping. The Emperor Angelfish feeds on their fleshy mantels and even a once a month attack can damage the clam, making it close up and slowly starve itself.
LPS corals will be under threat at all times and are grazed on just as commonly as algae. Only extremely noxious corals will be avoided. Anemones are sometimes safe in the same aquarium and will always be safe if they are hosted by a larger clownfish. Small clownfish may even be able to protect the anemone or at least dissuade the Emperor Angelfish from bothering it. This is a risk as the emperor may not tolerate the territorial behavior of the clownfish.
Leather corals and sea fans will also be under constant threat, as will feather dusters and worms. Shrimps and crabs will be left unharmed if they are over an inch and a half in size. This mostly means you cannot keep tiny decorative inverts like the sexy shrimp along side the Emperor Angelfish. Starfish will be safe but those with extremely long, flowing appendages may get nipped at a few times.
If you are unsure of the corals in your tank I would not suggest adding this angelfish to your tank. The loss of well established corals would not be outweighed by adding a single fish, no matter how beautiful they may be. It should be a simple task to identify the corals you have in the aquarium before adding an angelfish to your tank. You can then weigh the risks and rewards of adding the angel to your own aquarium.
Emperor Angelfish Diet
The Emperor Angelfish in the wild will spend a lot of its time grazing on corals, algae and sponges. They will also eat meaty foods like clams and other encrusted organisms. To replicate this in the home tank we should be feeding them a mostly herbivore diet with mixed in meaty foods like chopped meats, clams, live shrimp and seaweed attached to rocks or walls.
A good diet for the Emperor Angelfish should contain:
- Seaweed | Nori
- Pro-V Gelatin food
- High quality plant based flakes and pellets
- Foods made with sponge
- Algae flakes, pellets and wafers
- Gut loaded live shrimp
- Clams or oysters
- Spirulina
- Chopped squid
- Spinach or uncooked broccoli
Angelfish in general will need a decent amount of sponge based foods, which are typically sold as angelfish food. The Emperor Angelfish is not quite as dependent on sponges as other types of angelfish but should still have a decent amount added to their diet. Always feed their herbivore food before feeding any meats to ensure they get the nutrients they need. The Emperor Angelfish will be much quicker to eat meaty foods and will ignore plant based food, even sponge based foods, when both are fed at the same time.
An easy way to ensure their diet is well rounded is to use specially made foods like the new life spectrum, NLS, marine fish formula. Combined with high quality flakes, pellets and sponge based foods the Emperor Angelfish should be getting a good range of nutrition that they would be lacking with standard tropical fish flake foods. It is not advised to only use one type of food, even special blends so be sure to mix them up and keep multiple types of food. Three or four bottles along with the occasional meaty food is a good example.
Angelfish are frequently fed seaweed, which is a cheap and easy to feed food that provides them with a fair amount of nutrients. It is a good way to have them eating on display as you can stick the seaweed to the aquariums glass walls or any live rock you want them to hang around. Additionally the seaweed is typically sold dry, allowing us to use liquid nutrients to supplement any deficiencies the Emperor Angelfish may have.
The two things to remember about seaweed is their storage and removing seaweed from the tank. The air around the aquarium will typically be more humid than usual due to evaporation. Either store the seaweed away from the tank or in a container that will not let the seaweed suck in the humidity. All seaweed should be removed from the tank one hour after adding it. Uneaten seaweed will start to dissolve, fouling the tank water quickly. This is a big deal for the Emperor Angelfish who is highly dependent on having good water conditions to survive.
These angelfish are fairly competitive and should have no trouble eating around their tankmates. If anything they may cause trouble for the other fish, often preventing smaller, slow swimming fish form getting enough food. To combat this you can feed the tank in multiple areas at the same time, forcing the angelfish to pick an area to feed in.
Emperor Angelfish Tank Requirements
These angels, despite their large size enjoy swimming into caverns, in between and behind large rock structures. They are fairly maneuverable and will find their way into caverns they do not seem to fit into. Avoid making caverns with sharp points that the Emperor Angelfish may cut their scales on. It is unreasonable for every cavern to be large enough for them to swim into without touching the side, but they will learn which holes to swim into and which they cannot on their own. Just avoid ones that can hurt them and they will enjoy the rockwork you create.
In the wild they will spend a good portion of their time hovering above corals, sponges and various live rock with algae. Try to keep enough space above your live rocks for the Emperor Angelfish. They will not be afraid to touch the waters surface when trying to swim over rocks, which can give an interesting display in open top tanks. However this runs the risk of jumping as they touch the top of the water and grow accustomed to swimming so close to the surface. If you do have rocks near the top either have a tight fitting lid or keep the peaks of the rocks in the middle of the tank so they cannot easily jump out of the tank on accident.
The Emperor Angelfish does not use the sand in any way and can be kept in bare bottom tanks. Keep in mind that sand is typically a large home for beneficial bacteria and will help keep the tanks water more stable. If you do forego any type of substrate you may need to perform more frequent or larger water changes. They will typically need at least 30% of their water changed per month, which can be done all at once or twice a month in smaller amounts. Corals and macroalage will also reduce the need for water changes, but these are difficult to keep with this angelfish.
While the Emperor Angelfish handles tank transferring well they can easily be hurt when captured by nets. Their spines and gill covering spines are easy to catch on mesh materials. Damaging their gills can frequently lead to death where as their dorsal fin spines will cause a lot of stress and pain if they are torn on a net. Instead you should use a large container or bag to capture the angelfish. This can be done with either traps or just generally herding them in the direction of the container but can be tricky to do, as the Emperor Angelfish will typically avoid new objects in the tank.
Emperor Angelfish Tankmates
The Emperor Angelfish does well with similarly aggressive fish but should not be kept with other angelfish. Even much more docile angels are likely to be harassed by the emperor when swimming around the tank. Aggressive angels like the French Angelfish and queen will usually fight with the Emperor Angelfish and should not be kept together unless you have a large tank and a lot of experience with aggressive fish. Even then you should have a second tank ready to accept a rejected angelfish or be ready to return the angel. Keep in mind multiple tank transfers become increasingly stressful and will leave the removed fish in poor health even if no damage was done to them in the tank.
Corals and worms are always at risk when they are in the same tank as the Emperor Angelfish and should only be kept with extreme caution. Several of the SPS corals, especially noxious ones will be fine but should still be monitored. Worms are almost always targets and should not be kept. Small shrimp under one and a half inch are not safe and should also not be in the aquarium along side the Emperor Angelfish. Hard shelled crabs should be fine.
Good tankmates are:
- Clownfish
- Tangs
- Pufferfish
- Basslets
- Triggers
- Squirrel Fish
- Snappers
- Butterfly Fish
- Surgeon Fish
- Eels
- Wrasse
If you do choose butterfly fish be sure they are not too docile, as a weak willed butterfly fish can easily be harassed by the Emperor Angelfish. Stronger fish like triggers and puffers will not be in danger but can be chased off on occasion by an angry emperor. When this happens you can often hear the angelfish make a grunting noise, almost like a pig. It can be heard around 19 seconds in this video.
Eels make for good companions to the Emperor Angelfish as they will typically take residence in caverns that the angel would not be able to fit into anyways. Young Emperor Angelfish will sometimes pick slime off of eels, which can bother the eel but should not cause any damage. Eels are unlikely to hunt the emperor even when they are young unless they are exceedingly aggressive such as the Tessalata Eel.
Emperor Angelfish Gender & Breeding
There is no discernible difference between male and female Emperor Angelfish other than a slight varition in their facial mask. In females the lines around their mask is sometimes more grey than a males blue mask lines. This is not visible until they are much older, making pairing them a difficult task. Additionally they will not tolerate other Emperor Angelfish in their tank and a larger male will likely harass a smaller female. To keep a pair a large tank over 250 gallons is required to help reduce aggression.
As the Emperor Angelfish ages they change color completely. As a juvenile they will be black covered with electric blue stripes all across their body. Their fins will be a light blue. Eventually the top of their body will begin to show signs of yellow as their body slowly shifts over to the blue and yellow body that is expected from the Emperor Angelfish. This should take just over two years or around 40 months from their birth. This long and intense transformation is one of the main reason people are so keen on keeping them.
Unfortunately these angels are not bred in captivity. This keeps their purchase price high, as they are not found in large quantities in the wild. They are not at risk of endangerment so it is not harmful to their population to support wild collection of them. These fish will often live for 15 to 20 years in the home aquarium when properly cared for and are not typically caught using harmful chemicals that we often see with smaller fish.