Bicolor Angelfish (Centropyge bicolor)

A dwarf angelfish for an established marine aquarium

The Bicolor Angelfish (Centropyge bicolor) is a dwarf marine angelfish in the angelfish family Pomacanthidae. It comes from the Indo-Pacific, from East Africa to the Samoan and Phoenix Islands, north to southern Japan, south to New Caledonia and throughout Micronesia. FishBase records a maximum length of 15 cm total length, so every tank and stocking decision should be made for a fish of that size. It suits a keeper who already runs a stable, well-filtered saltwater aquarium and wants one dwarf angelfish as a centrepiece, added near the end of stocking.

On the reef it lives in lagoons, channels and protected seaward reef slopes, around drop-offs and in coral and rubble areas, between 1 and 25 m deep. Wild fish are usually seen in pairs or small groups, dart from one hiding place to the next and feed on algae, small crustaceans and worms. That behaviour shapes the aquarium you need: plenty of rock to hide in and pick over, clean and stable marine water, and companions calm enough to let it move about.

The species is commonly exported through the aquarium trade and is listed as Least Concern by the IUCN. Tropical Fish Co rates it advanced, mainly because it needs a mature marine system, more space than its arrival size suggests and a stocking plan built around one territorial dwarf angelfish.

What each purchase supplies

Each purchase supplies one Bicolor Angelfish in the size you pick on the product page: 4–6 cm, or the larger size shown as >6, meaning over 6 cm. The size you select is the size supplied, not the adult size. Whichever you choose, set the aquarium up for the 15 cm maximum rather than the length it arrives at. The larger size is the same species with the same care needs, not a different form.

Sex is guaranteed only when the selected option explicitly states male or female. This Bicolor angelfish listing has no sex-guaranteed option. OATA notes that it can be very difficult to tell the sex of dwarf angelfish unless they are in breeding condition, which is one more reason to plan for a single fish rather than trying to build a pair.

You may see this species sold under other names. Wikipedia lists Pacific rock beauty, oriole angelfish, oriole dwarf angel, blue and gold angel and two-colored angel, and OATA spells it bicolour angelfish. Every one of those names refers to Centropyge bicolor, and the scientific name is the reliable way to confirm you are reading about the same fish.

The gallery photograph shows a fish with a bright yellow head, forebody and tail and a deep blue rear body, over dark gravel in front of rockwork. Gallery images have been digitally enhanced to improve image quality. Natural colour, pattern, size and maturity can vary between live animals.

Three questions to answer before you buy

Most problems with dwarf angelfish start before the fish is ordered, so settle these three points first.

1. Is the aquarium big enough and mature enough? OATA's minimum of at least 120 litres is for a single dwarf angelfish of a smaller species. This one reaches 15 cm, and every companion adds to the space needed. The filter should already hold ammonia and nitrite at zero.
2. Is there already a dwarf angelfish, or a similar species, in the tank? If so, choose a different fish. OATA advises one dwarf angelfish per aquarium unless it is particularly large with lots of visual barriers.
3. Could you accept some nipping of corals or clams? Some individuals may nip them. A fish-only aquarium with plenty of rock avoids the question; a reef keeper needs to decide in advance.

If all three answers point the right way, the care sections cover water values, feeding, the weekly routine and arrival day in the order you will need them, and the compatibility sections explain how to build a calm community around it.

Plan the aquarium around the 15 cm adult

Tank size

OATA's general rule is to buy an aquarium as large as you reasonably can. It recommends an aquarium of at least 120 litres for a single individual of the smaller dwarf angelfish species, and says aquariums need to be larger if you want to keep dwarf angelfish with other species. The same sheet contrasts the cherub angelfish, which grows to about 8 cm, with the bicolour, which is unlikely to grow over 15 cm. This fish sits at the larger end of the group, so 120 litres is a floor, not a target.

A worked example makes the point. If you run a 120 litre marine tank and plan to add the angelfish to clownfish and a basslet, OATA's guidance already points you towards a larger aquarium, because 120 litres is the minimum for one dwarf angelfish of a smaller species on its own. A bigger tank also gives more stability in temperature and water quality, which OATA gives as one of the reasons to buy as large as you can.

Rockwork and hiding places

OATA describes dwarf angelfish as relatively undemanding in terms of décor but recommends plenty of live or artificial rockwork. Build it with this fish's wild habits in mind. It darts from one hiding place to the next, so give it several separate caves and overhangs with short gaps of open water between them, rather than one solid wall of rock. In the wild dwarf angelfish spend much of their time swimming around the reef looking for food, and rock surfaces give this one somewhere to pick over between meals.

Spread the hiding places along the length of the tank. When the angelfish claims one area, the other fish still have cover of their own, which helps a territorial fish and its companions share the space.

Filtration and skimming

Whatever the size, a filter is essential. For a marine set-up OATA lists three workable approaches: live rock with sufficient water flow, an internal or external filter, or a sump-based filter. A protein skimmer can also help, because it removes dissolved organic waste before that waste breaks down into more harmful substances. Choose the approach you can maintain every week, since a neglected filter protects nothing.

Keep marine water values steady

Keep the aquarium at 24–26°C, pH 7.9–8.3 and salinity 1.020–1.025. These are OATA's suggested parameters for dwarf angelfish, a general guide for the group rather than a species-specific optimum, and OATA describes dwarf angelfish as usually undemanding of water chemistry. The full set is below.

Reef aquariums

OATA adds that if you keep dwarf angelfish in a reef aquarium, some parameters will need to be altered to accommodate more sensitive species. In practice that means setting the reef's values for its most demanding corals and invertebrates while staying inside a range the angelfish tolerates, and checking with us if the two pull in different directions.

What to do when a reading moves

• Ammonia or nitrite above zero: hold off adding any new fish, check you are not overfeeding, and test again. OATA warns that dwarf angelfish can be stressed by even the smallest amounts of ammonia and nitrite.
• Nitrate climbing towards 50 mg per litre: look at feeding amounts and make sure the weekly partial water change has not slipped.
• Temperature outside 24–26°C: check the heater and the room, and bring it back gradually rather than with a sudden correction.
• Salinity drifting: bring it back into 1.020–1.025, and match the salinity of new salt water to the tank at each change.

Stable numbers inside these ranges are the goal. A marine angelfish copes far better with a tank that holds steady at 25°C than with one that swings across the whole range from day to day.

Mature the filter before the angelfish goes in

The RSPCA describes filters as vital for removing waste, and says no fish should be kept without a well set up and maintained filter. Fish release ammonia, which is toxic. A working biological filter lets beneficial bacteria grow, and those bacteria convert ammonia to nitrite, which is also toxic, and then to nitrate, which is safer. A marine tank depends on that chain just as a freshwater one does.

Why new tanks cause trouble

OATA explains that the bacteria established while maturing a filter need to increase every time more fish are added and feeding goes up. Overstocking, or stocking too quickly, causes new tank syndrome: there are not enough nitrifying bacteria to cope with the extra waste, ammonia and nitrite rise, and fish become ill or die. Increase the number of fish slowly, and give the filter time to catch up after each addition.

This matters twice over for a dwarf angelfish. It should be one of the last fish added, which suits a mature system well, and OATA notes that ammonia and nitrite stress can lead dwarf angelfish to develop various diseases.

Ready-to-order checklist

• The aquarium has run with live rock, a filter or a sump long enough to show zero ammonia and zero nitrite.
• Nitrate is below 50 mg per litre.
• Temperature sits at 24–26°C and salinity at 1.020–1.025.
• The rockwork offers several separate hiding places.
• The fish already in the tank have settled, and no other dwarf angelfish or similar species is present.
• The tank is sized for a 15 cm adult and the companions it will live with.

If any item on that list is still open, finish it first. Waiting for a filter to mature is far easier than nursing a stressed angelfish through poor water.

Feed a varied diet of meaty foods and algae

FishBase records that wild Bicolor Angelfish feed on algae, small crustaceans and worms, and OATA notes that dwarf angelfish in the wild spend much of their time swimming around the reef looking for food. Build the aquarium diet on the same two halves: meaty foods that stand in for small crustaceans and worms, and vegetable matter that stands in for algae.

How much and how often

OATA's advice for dwarf angelfish is to feed only what they can eat within a few minutes, twice a day. Take care not to overfeed: uneaten food builds up and breaks down, releasing toxic waste into the water. In a tank with other fish, watch the angelfish itself at feeding time rather than judging by how quickly the food disappears, because faster companions can take the lion's share.

Reading its appetite

Reduced feeding or a lack of interest in food is on OATA's list of early warning signs, so treat appetite as a daily health check. A fish that feeds eagerly twice a day, picks at the rock between meals and holds its body condition is doing well. If a new arrival is slow to take frozen foods at first, keep offering the variety above in small amounts, remove what it leaves, and test the water, as OATA advises whenever feeding or behaviour changes.

Rotate the foods through the week rather than relying on one. Variety is the core of OATA's feeding advice, and it covers both halves of a diet that, in the wild, includes algae as well as small animals.

Build a weekly maintenance routine

OATA strongly recommends a 25% partial water change at least once every week, using a siphon to lift solid waste from the gravel. In a 120 litre aquarium that is 30 litres each week; in a larger system, work out the same quarter of your own volume and keep to it. Holding the same quarter every week keeps the routine easy to follow, and your test results show whether it is enough.

Looking after the filter

Check and clean filters regularly so they do not block. When filter media needs cleaning, do not run it under the tap, because any chlorine or chloramine present may kill the beneficial bacteria. Rinse it lightly in the tank water you have just removed during the water change instead, so fewer bacteria are lost. Clean the protein skimmer regularly as well, as a dirty skimmer loses performance.

A simple weekly sequence

1. Test ammonia, nitrite and nitrate, and note the results.
2. Check temperature and salinity against 24–26°C and 1.020–1.025.
3. Siphon out a quarter of the water, taking solid waste from the gravel with it.
4. Rinse filter media in the removed water if it needs it, never under the tap.
5. Refill with prepared salt water matched to the tank.
6. Clean the skimmer cup and check that water flow through the rockwork is unobstructed.

Good husbandry is essential with dwarf angelfish, which is why this routine carries as much weight as the tank itself. A written log of your weekly readings makes slow changes easy to spot long before the fish shows them.

Arrival day, from sealed parcel to release

Your angelfish is hand-packed by our team: hand-bagged in pure oxygen, in an insulated poly box, with a heat pack when the weather calls for it. We email the tracking number and your confirmed delivery date, and a licensed live-animal courier carries the parcel on a tracked service. The full terms are on our delivery and Live Arrival Guarantee page.

Step by step on the day

1. Make sure someone is at the delivery address to receive the parcel, because live fish cannot be left unattended.
2. If practical, start filming before the parcel is opened: one continuous video showing the parcel still sealed with the outer box visible, you opening it, and the fish still inside the sealed bag. If practical, film the delivery this way.
3. Open and inspect the parcel the same day it arrives.
4. Float the bag for 20–30 minutes before releasing the fish.
5. Never pour the bag water into your tank.
6. If anything has gone wrong, contact us the same day by email sending your order number and clear photos or an optional video, and we will review your claim under our Live Arrival Guarantee and arrange the appropriate replacement or refund.

The Live Arrival Guarantee needs someone at the address to receive the parcel, the parcel opened and inspected the same day it arrives, and clear photos or an optional continuous unboxing video showing the parcel still sealed. The video makes claims quicker and fairer, and our courier may request it when we raise a claim. We strongly recommend an unboxing video when practical: it helps us investigate arrival concerns faster, resolve them with less back-and-forth and understand packing or transit issues so we can reduce recurrence. Video is optional and clear photos are accepted. Never delay necessary animal care to record evidence.

Aquarium checks before release

OATA advises checking that ammonia and nitrite are at zero before adding any fish, so test the aquarium on the morning the parcel is due rather than after the bag is floating. Once the angelfish is in, use OATA's description of a healthy fish as your first check: clear bright eyes, undamaged fins, intact scales, no ulcerations or bumps, and appropriate swimming behaviour. Brief dashes between rocks are normal for this species; a fish that stays wedged in one spot and refuses food over the following days needs closer attention.

Health checks for the first weeks and beyond

All fish vary slightly in behaviour and appearance, but OATA recommends watching for changes in the following, so that problems are caught before they become a real health issue.

• Swimming: hanging at the surface, sitting on the bottom or erratic swimming.
• Colour: turning darker or paler than normal.
• Temperament: more aggression, or hiding more than usual.
• Breathing: gill covers moving faster or slower than normal.
• Appearance: white spots, fluffy growths, or loss of fins or scales.
• Condition: gaining or losing body weight.
• Feeding: eating less, or losing interest in food.

Knowing what normal looks like

A Bicolor Angelfish that darts from one hiding place to the next is behaving as it does on the reef. That is different from a fish that hides more than it did last week, or stops coming out to feed. Spend a few minutes each day watching it at feeding time, when most of the signs above are easiest to see.

Checkpoints after introduction

• First few days: it should start darting between hiding places and showing interest in food. A fish that stays hidden and ignores every offering needs a water test.
• First week: test ammonia and nitrite again, because OATA explains that filter bacteria have to increase each time a fish is added and feeding goes up.
• First month: check that its body condition holds, that it feeds at both daily meals, and that its territorial behaviour towards companions has settled rather than grown.

What to do first

If something changes, test your water quality before anything else, as OATA advises for any of the signs above. Then contact us with the readings and a description of what you have seen, and we will help you work out the next step.

OATA notes that dwarf angelfish can live for many years in a well-matured set-up with good water quality. The weekly routine, a steady feeding pattern and daily observation are how you give it that set-up.

Keep one dwarf angelfish per aquarium

OATA's compatibility advice is clear: most dwarf angelfish will not tolerate other members of the same species or similar species, so it is best to keep one per aquarium unless the aquarium is particularly large with lots of visual barriers. For almost every home aquarium, that means one Bicolor Angelfish and no other dwarf angelfish alongside it.

Why a pair is not the plan

FishBase notes that wild fish are usually seen in pairs or in small groups. That describes fish with a whole reef to spread across, not a stocking target for a closed tank. Sex cannot be chosen when you buy, and dwarf angelfish are very hard to sex outside breeding condition, so an attempt at a pair is really two fish of the same species sharing a territory.

Similar species count too

OATA's warning covers similar species as well as the same one. Treat other dwarf angelfish, such as the flame angelfish (Centropyge loriculus), the coral beauty (Centropyge bispinosus) or the cherub angelfish (Centropyge argi), as incompatible in a normal home aquarium.

Add it last

Dwarf angelfish should generally be added last, because they can become territorial in aquariums. A fish that arrives into a tank where the other residents already hold their own spaces has less room to claim the whole aquascape. If you are still building the rest of the community, choose and settle those fish first, then bring the angelfish in as the final addition.

Choose calm community fish as companions

Dwarf angelfish are not as boisterous as their larger relatives, and OATA says most species can be mixed in a relatively calm community, with species like clownfish, gentler damsels and small basslets. Those are the kinds of fish to build around. Before buying, ask us with a list of what is already in your tank and its volume, and we will check the combination with you.

Planning the order of stocking

Choose the calm companions first and let the filter mature to their waste before the angelfish goes in. You can browse our marine fish collection while you plan, and it helps to decide on the full community before the first fish arrives rather than adding species one by one without a plan. The angelfish then arrives into a settled tank as the last addition, which is exactly where OATA places it.

Space still decides the outcome

Every companion adds to the space the tank needs. OATA's 120 litre minimum refers to a single dwarf angelfish of a smaller species with no other fish, and the sheet asks for a larger aquarium as soon as other species share it. Plan the volume for a 15 cm angelfish plus its companions at their adult sizes, and give each fish its own share of rock to shelter in.

Corals, clams and other invertebrates

A reef aquarium needs more thought. OATA advises always checking before mixing a dwarf angelfish with invertebrates, because some individuals may nip on corals and clams, and some dwarf angelfish will prey on invertebrates they find in the aquarium. The wild diet FishBase records for this species, algae, small crustaceans and worms, shows that small animals living in the rockwork are part of what it looks for.

Deciding for your tank

• Fish-only aquarium with rock: the simplest home for it, with no corals or clams at risk.
• Reef where some nipping of corals would be tolerable: possible, but watch the angelfish closely after introduction and plan what you would do if it starts to nip.
• Reef with prized clams or corals: weigh the risk seriously before buying, because nipping depends on the individual and cannot be ruled out in advance.
• Small crustaceans and worms in the rockwork: expect the angelfish to hunt some of them, as it would on the reef.

Water values in a reef

Remember OATA's note that a reef aquarium may need its parameters altered to suit more sensitive species. Set the reef for its invertebrates while keeping temperature, pH and salinity inside the values described in the care section, and include every coral, clam and other invertebrate in the stock list you send us before ordering.

Common questions from marine keepers

How big does a Bicolor Angelfish grow?

FishBase records a maximum length of 15 cm total length for this species, and OATA says the bicolour is unlikely to grow over 15 cm. Plan the aquarium, the rockwork and every companion for that adult length rather than the length of the fish on the day it arrives.

What size aquarium does it need?

OATA recommends an aquarium of at least 120 litres for a single dwarf angelfish of the smaller species, and a larger one when other fish share the tank. This fish reaches 15 cm, so treat 120 litres as the starting point and choose a larger, well-filtered marine aquarium with plenty of rockwork.

How many Bicolor Angelfish can I keep together?

Keep one per aquarium. OATA advises that most dwarf angelfish will not tolerate other members of the same species or similar species, so one is best unless the aquarium is particularly large with lots of visual barriers. FishBase notes that wild fish usually live in pairs or small groups, which describes life on an open reef rather than a stocking target for a home tank.

Is the Bicolor Angelfish suitable for beginners?

We rate it as an advanced fish. It needs an established marine aquarium with steady salinity, pH and carbonate hardness, zero ammonia and nitrite, more space than OATA's 120 litre minimum for the smaller dwarf angelfish, and a keeper who will test the water and make a 25% partial water change at least once every week.

What does a Bicolor Angelfish eat?

In the wild it feeds on algae, small crustaceans and worms, according to FishBase. In the aquarium, offer a varied diet of meaty frozen foods such as mysis shrimp, enriched brine shrimp or krill alongside vegetable matter such as nori, and try pellet and flake foods too. Feed only what it can eat within a few minutes, twice a day, as OATA advises for dwarf angelfish.

What temperature and pH does it need?

OATA's guidance for dwarf angelfish as a group is 24–26°C, pH 7.9–8.3, salinity 1.020–1.025 and carbonate hardness 8–12 dKH, with ammonia and nitrite at zero and nitrate not exceeding 50 mg per litre. Hold those values steady in an established marine aquarium rather than chasing small changes.

Is the Bicolor Angelfish aggressive, and does it nip?

It is territorial rather than boisterous. OATA describes dwarf angelfish as less boisterous than their larger relatives but able to become territorial in aquariums, which is why it should go in last. Some individuals may nip corals and clams, and some dwarf angelfish will prey on invertebrates they find in the aquarium.

Which fish and invertebrates can it live with?

In a relatively calm community, OATA names clownfish, gentler damsels and small basslets as the kind of fish most dwarf angelfish can mix with. Keep other dwarf angelfish and similar species out unless the aquarium is particularly large with lots of visual barriers, and treat corals, clams and other invertebrates as a risk rather than a certainty.

How does a Bicolor Angelfish arrive alive in the UK?

If practical, start filming before the parcel is opened: one continuous video showing the sealed box, the opening and the fish still inside its sealed bag. It travels hand-bagged in pure oxygen in an insulated poly box, with a heat pack when the weather calls for it, carried by a licensed live-animal courier. Someone must be in to receive it; open and inspect it the same day, float the bag for 20–30 minutes before releasing the fish, and never pour the bag water into the tank. If anything has gone wrong, contact us the same day with your order number and clear photos or an optional video for a replacement or refund.

Sources for this care guide

• FishBase: Centropyge bicolor, for identity, family, distribution, wild habitat and depth, wild diet and behaviour, maximum recorded length and IUCN status.
• Wikipedia: Bicolor angelfish, for the alternative common names.
• OATA: How to look after dwarf angelfish, for group guidance on water values, aquarium size, filtration, feeding, maintenance, introduction, health signs and compatibility.
• RSPCA: fish environment, for filtration and the conversion of ammonia to nitrite and nitrate.
• Tropical Fish Co delivery and Live Arrival Guarantee page, linked in the arrival section, for packing, courier and claim steps.