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Emperor Angelfish: Everything You Need To Know

Emperor Angelfish: Everything You Need To Know

The emperor angelfish (Pomacanthus imperator) is a stunning addition to any home aquarium. Its striking bright blue and yellow stripes make it an eye-catching showpiece. However, there’s much more to this unique species than its beautiful appearance.

Emperor angelfish are highly active fish, often seen darting around the tank for food. They are semi-aggressive, so do not keep them with peaceful fish. Ideally, you should keep them by themselves unless you want them to mate. They can live for more than 20 years.

In this article, we will look at how to care for these regal fish, exploring their habitat requirements, suitable tank mates, dietary preferences, potential health concerns, and tips for ensuring their well-being in your saltwater tank.

Emperor Angelfish Species Profile

The majestic emperor angelfish is a popular species of saltwater fish. The fish is native to coral reefs in the Indo-Pacific region, ranging from East Africa and the Red Sea to Hawaii, Japan, and Great Barrier Reef in Australia.

  • Common name: Emperor Angelfish
  • Scientific name: Pomacanthus imperator
  • Care level: Moderate to difficult
  • Size: 12 inches (30.48 cm)
  • Lifespan: 10-15 years
  • Temperament: Semi-aggressive
  • Diet: Omnivore
  • Group size: One emperor angelfish t per tank, but two can be kept if the tank is large enough
  • Minimum tank size: 100-220 gallons (378.5-832.79 liters)
  • Tank level: Any level
  • Water temperature: 73-78°F (22.78-25.56°C) 
  • Water pH levels: 8.1 – 8.4
  • Water hardness: 8-12 dKH
  • Specific gravity: 1.020–1.025 SG

The species can also be found in the eastern Pacific – from the Gulf of California to Peru. It’s popular in public and home aquariums due to its striking coloration and pattern. In the wild, they usually inhabit coral reefs, lagoons, and seaward reefs, where they search for food. 

They’re typically found in pairs or large groups but may be found alone, especially when they reach maturity. These fish prefer depths of one to 100 meters (3.28 to 328 feet). Adults can be found in lagoons and coastal reefs where the waters are calmer. 

On the other hand, juveniles are usually found in the shallow areas of lagoons, bays, and other sheltered inshore areas as they’re more vulnerable to predators. The subadults inhabit the surge zones of outer reefs where there’s increased availability of food sources. 

Although this species isn’t considered rare, it does face threats from habitat destruction and overharvesting for the aquarium trade.

Emperor Angelfish Appearance & Size

The emperor angelfish is a beautiful animal. It has a deep-bodied oval shape, a sharp caudal peduncle, and a straight head profile. It has a white base color and is covered in vertical blue stripes with yellow margins, giving it a unique pattern. 

The head has a yellow-orange face and a black spot on the forehead. The fins are bright blue, and the caudal fin is outlined in yellow. Although adults and juveniles don’t have the same coloration, they have similarly shaped bodies and heads. 

Juveniles have a black and white and royal blue coloration in an arch pattern on their bodies and spots on their fins. This species is active, curious, and inquisitive by nature. It will often be seen searching the substrate for food and checking its surroundings. 

The adult size of emperor angelfish is approximately 12 inches (30.48 cm) in length. They can reach a larger size of 15 inches (38.1 cm) in the wild, but their maximum size in captivity is usually limited to 12 inches (30.48 cm) due to space constraints.

Difference Between Males & Females

The males are usually larger than the females and have a more elongated dorsal fin. They tend to be more brightly colored, with a blue head and yellow body, while the females have duller coloration. 

Adaptations and Protection

The emperor angelfish has several adaptations to protect itself from predators:

  • Camouflaging pattern that helps them blend in with the reef environment
  • Defensive behavior of hiding and rapidly swimming away if they sense danger 
  • Puffing up their bodies to make them appear larger and to intimidate potential predators 
  • Long dorsal and pectoral fins, which help them quickly dart away
  • Ability to rapidly change direction in the water, making them difficult to catch

Personality and Behavior

These fish will be most active in the morning and evening but can become quite bold during the day and tend to ignore other fish species unless they’re too close, in which case they may become territorial.

They’re semi-aggressive and can be kept in a larger tank with other species. You should keep one emperor angelfish per tank, as they’re known to become aggressive and fight with others of their species. 

They may attack invertebrates such as snails, shrimp, and crabs. They’re also known to try and eat smaller fish, so it’s important to know the size difference between the emperor angelfish and any other species you put in the same tank with them. 

As it’s known to be a bolder species, it’s important not to overcrowd the aquarium with too many other species that could cause stress to the emperor angelfish. It does best in an aquarium with plenty of places to hide and explore.

Average Lifespan

Emperor angelfish are long-lived fish and can live for up to 20 years in the wild. In captivity, they can reach a maximum lifespan of 10 to 15 years. 

Emperor Angelfish Care & Tank Set Up

Emperor angelfish are moderately difficult to care for, as they require a large aquarium to provide the space and swimming area they need. These fish are active swimmers, so a long tank is ideal.

Tank Size

The emperor angelfish prefers a large tank of at least 100 gallons (378.5 liters). A fully grown one needs 220 gallons (832.79 liters) with plenty of live rock and hiding places. You should provide plenty of open swimming space.

Water Parameters

When establishing a saltwater tank, it is essential to closely emulate their natural ocean environments. Emperor Angelfish are highly sensitive to even minor changes from their natural conditions, and such changes can lead to negative responses in their behavior and well-being.

  • Water temperature: 73-78°F (22.78-25.56°C) 
  • Water pH levels: 8.1 – 8.4
  • Water hardness: 8-12 dKH
  • Specific gravity: 1.020–1.025 SG

It is important to ensure stable and appropriate levels of temperature, salinity, pH, and water quality. The recommended temperature range for Emperor Angelfish is between 72°F to 82°F (22°C to 28°C), with a salinity level of 1.020 to 1.025. 

Maintaining a stable pH range of 8.1 to 8.4 is also crucial. Additionally, regular monitoring and filtration to maintain pristine water quality are necessary, as these fish are sensitive to ammonia and nitrate levels.

Check your fish regularly for signs of disease, such as white spots or cloudy eyes. A UV sterilizer may be beneficial to keep your water quality in check. The emperor angelfish are sensitive to water quality and can be easily affected by environmental changes. 

When it comes to UV sterilizers, my best pick is the AA GKM24W Internal UV for Aquariums (available on It’s suitable for aquariums of up to 120 gallons (454 liters), which is the minimum amount of water an emperor angelfish needs. Plus, you can install it without specialized tools, and it can last up to nine months before the bulbs need to be replaced. 

How To Set Up Their Tank

They can be kept in a reef tank, though they may nip at stony and soft corals. They appreciate a well-oxygenated tank with plenty of water flow and good circulation. 

The bottoms should be covered with sand, crushed coral, or live rock, as these provide natural hiding places for the clams, sea stars, and crustaceans this species feeds on. 

The tank should have a good filtration system and regular partial water changes should be done to keep the ammonia, nitrite, and nitrate levels low. Lights should be kept at a moderate level as this species prefers dimly lit conditions. 

Avoid strong currents, as the emperor angelfish cannot swim against them and may become stressed. 

The water should have a moderate flow, with good circulation and plenty of oxygenation. You can use live rock to create hiding places, crevices, caves, and ledges for them to explore.

Emperor Angelfish Tank Mates

The emperor angelfish is a solitary species and should not be kept with other angelfish, as it will become highly territorial. However, you can keep a male and female pair together, providing plenty of hiding places for each. 

The emperor angelfish can be aggressive with smaller tank mates and should be kept with species such as wrasses and dottybacks. You can keep them with other large semi-aggressive fish such as tangs and angelfish. 

Tank Mates To Avoid

Avoid small, peaceful fish such as gobies and dwarfs, as the emperor angelfish may decide to make a snack out of them. 

They’re best suited to a larger aquarium, where they can establish their own territory and not bother other fish. It’s best to add all the tank mates at once, as this will prevent aggression between the emperor and other fish being added later.

Diet and Feeding Habits

The emperor angelfish is an omnivore: Their diet includes algae, zooplankton, and small crustaceans. They feed primarily in the water column and on substrate surfaces, though they have also been observed consuming corals. 

In the wild, they feed on sponges, tunicates, hydroids, and planktonic material. The optimal diet for emperor angelfish in captivity should include a variety of meaty foods such as live brine shrimp and frozen Mysis, as well as quality flake food. 

They enjoy grazing on algae on rocks and glass in the aquarium. To supplement their diet, include some vegetable matter such as seaweed and spirulina. Feed your emperor angelfish two to three times a day, providing only as much food as they can consume within a few minutes.

It’s especially important to not overfeed this species, as they’re prone to obesity. For best results, feed the fish with a turkey baster, or use a feeding stick. This will help ensure they receive the full nutrition they need while avoiding excess food waste in your tank.

Like many other fish species, emperor angelfish form a “cleaning station” where other fish can come to have parasites and bacteria removed from their bodies. If your angelfish are setting up a cleaning station in your tank, they may require more frequent feedings. 

Monitor your angelfish closely and adjust their diet accordingly. You should vary their diet and not rely too heavily on any one type of food. Variety will ensure they get all the necessary nutrients, vitamins, and minerals needed for their health. 

Quality flake or pellet food should form the foundation of their diet. Offering them frozen, fresh, or live food as treats will keep them interested and help with training.

If you want a tasty treat for your fish that will also help enhance their color, I recommend the Fluval Color Enhancing Flakes Fish Food 35gm, 1.23-Ounce (available on It’s specially designed for saltwater fish like the emperor angelfish and is packed with nutrients your pet needs to stay healthy. 

Breeding Emperor Angelfish

Emperor angelfish breed during the summer months. They form pairs and can be seen swimming side-by-side in shallow lagoons and reefs. To lay their eggs, they select a flat surface to attach them, such as a rock or coral head. 

The pair will guard their eggs until they hatch. The young fish will hatch with the ability to swim and feed independently, but the parents remain nearby for protection. Emperor angelfish will typically return to the same area in subsequent breeding seasons.

Little is known about their breeding in captivity, as it’s difficult to breed them in an aquarium environment. If you want to attempt breeding emperor angelfish in your tank, ensure you have a larger, well-oxygenated tank. 

Provide hiding places and plenty of food to make them more likely to breed. Use a reliable water testing kit, as changes in water chemistry can cause the fish to become stressed and less likely to breed. 

The males have longer filaments on their fins and a nuchal hump, a bump on the forehead that becomes more prominent when they reach sexual maturity. The females don’t have this bump.

How To Choose an Emperor Angelfish for Your Aquarium

When choosing an emperor angelfish for your aquarium, there are a few factors to look for. 

  • Healthy fish. An active fish that feeds well and has bright colors is usually a sign of good health. Avoid any weak or inactive fish, as this could indicate health issues or ones that show discolored skin patches and cloudy eyes. Sick fishes may not survive in captivity for long and should therefore be avoided.
  • Size. Choose a fish that’s the appropriate size for your tank. Emperor angelfish can reach up to 12 inches (30.48 cm) in captivity, so you must have enough space for the fish to swim comfortably. The size of the fish will tell you its age and how long it will live in captivity.
  • Personality. Personality can play a role in how your fish will succeed in captivity. Ideally, your emperor angelfish should be active, inquisitive, and has an overall pleasant demeanor. A fish that’s responsive to your presence and curious about its surroundings is usually a good choice. Avoid any aggressive or shy fish, as these traits may cause problems in the aquarium. 
  • Color. The coloration of the emperor angelfish can vary, meaning some fish may be more colorful than others. Get a fish that has bright colors and clear markings. The brighter the colors, the more impressive your fish will look in the aquarium. 
  • Spawning. If you’re looking for a breeding pair, check to see if the fish have spawning behavior. Spawning behavior usually consists of courtship rituals, swimming, and chasing, and is a good indication that a pair are compatible and should be kept together. 

Wrapping Up

The emperor angelfish is a beautiful and intriguing fish species that can be an impressive addition to any aquarium. When choosing one of these fishes for your tank, consider its health, size, personality, color, and spawning behavior to ensure you get the best pet possible. 

With the right water conditions, good nutrition, a compatible tankmate, care, and attention, you can enjoy watching the emperor angelfish for many years to come. Keeping this species of fish can be a rewarding experience and will give you the chance to witness their unique behaviors up close.

I’m Elle, the founder of FishHQ. I created this website to share knowledge, tips, and inspiration for beginner hobbyists to help them create a healthy, happy, and vibrant environment for their fish to thrive. Read more...