Blue Angelfish Mix (Pterophyllum scalare)

A blue colour form of the freshwater angelfish

The Blue Angelfish Mix (Pterophyllum scalare) is a blue-toned colour form of the freshwater angelfish, a tall, flat-sided cichlid from the Amazon basin of South America. Plan for an adult of about 15 cm in length and roughly 20–25 cm from fin tip to fin tip. It suits a keeper with a mature, tall aquarium of about 200 litres who will keep it as part of a compatible pair or a planned group in a calm, robust community.

FishBase places it in the family Cichlidae and records it across the Amazon River basin in Peru, Colombia and Brazil, along the Ucayali, Solimões and Amazon rivers, in rivers of Amapá in Brazil, the Rio Oyapock in French Guiana and the Essequibo River in Guyana. Adults live in swamps and flooded ground where aquatic and riverside vegetation is dense and the water is clear or silty, and their colour is deeper in clear water. It is one of the most popular of all tropical aquarium fish and is listed as Least Concern by the IUCN.

Eschmeyer's Catalog of Fishes gives the accepted name as Pterophyllum scalare (Schultze, 1823), with the lower Amazon in Brazil as its type locality. The altum angelfish, Pterophyllum altum, is a separate species rather than a colour strain. Marble, koi, gold, black and platinum angelfish are domestic colour forms of this one species, and the blue mix is sold under the same scientific name, so its care is simply the care of Pterophyllum scalare.

What one purchase brings, and how many to buy

Each purchase supplies one live angelfish from the blue mix. The trade name covers blue-toned fish, and individual fish differ in shade and pattern, so expect a blue angelfish of this species rather than a copy of the photograph. Colour is not a care rating either: our care guide treats no colour form as universally hardier, calmer or more disease-resistant than another, so this fish needs exactly the aquarium and routine of any other Pterophyllum scalare. Plan that aquarium for the adult fish, not for the size it is when it arrives.

OATA advises keeping angelfish in a group or as a pair at minimum, and warns that a single angelfish may become stressed. Decide how many you will keep before you order, then buy that number. If you would like to compare other colour forms of the same species for a mixed group, our angelfish collection shows the forms we sell alongside this one.

Sex is guaranteed only when the selected option explicitly states male or female. This Pterophyllum scalare blue mix listing has no sex-guaranteed option. Sexing freshwater angelfish is difficult. Seriously Fish notes that males have a smaller, pointed genital papilla, but it can usually be seen only when the fish are spawning, and our care guide treats forehead shape, fin angle or temperament as unreliable sex tests in young fish. Pairs have to form between the fish themselves, which the compatibility section explains.

Key numbers at a glance

• Adult length: about 15 cm, with fins making it roughly 20–25 cm tall.
• Aquarium: about 200 litres, 100 × 40 cm and at least 50 cm tall for an adult pair.
• Water: 24–27°C, pH 6.5–8.0 and 5–12 dGH, held steady.
• Company: a compatible pair at minimum, never one fish alone by default.
• Feeding: what it can eat within a few minutes, once a day.

The photograph shows a blue angelfish with tall, swept-back dorsal and anal fins, swimming among feathery green stem plants. Gallery images have been digitally enhanced to improve image quality. Natural colour, pattern, size and maturity can vary between live animals.

How big it grows, and why height matters

Every planning decision on this page uses 15 cm as the adult length. Seriously Fish records 150 mm standard length, FishBase also gives 15 cm total length, and our care guide uses 15 cm total length as the commonly cited figure. FishBase's current field maximum is smaller, at 10.5 cm total length, but a planning figure has to cover the bigger fish.

Length is only half the picture. The extended dorsal and anal fins can make an adult roughly 20–25 cm tall from fin tip to fin tip, so a fish that looks small in a shop tank needs real height at home. Seriously Fish recommends a tall tank of at least 50 cm for adult fish, and OATA says angelfish need an aquarium that is sufficiently tall once they are fully grown.

Three measurements to check

• Height: a tank at least 50 cm tall, so an adult can hold its fins clear of the substrate and the surface.
• Footprint: a base of 100 × 40 cm, the Seriously Fish figure, gives a pair room to move and claim space.
• Turning room: open water where an adult can turn without dragging its fins through decor.

OATA notes that American cichlids can live for several years in a well-matured set-up with good water quality, so the tank you choose now is the tank this fish will live in for a long time. Buy for the adult from the start.

Choose the tank for the pair or group you will keep

Seriously Fish describes an aquarium of 100 × 40 × 50 cm, about 200 litres, as the smallest to consider. OATA's figures bracket it: it recommends at least 120 litres for a pair of smaller American cichlids, under 15 cm, and at least 300 litres for larger or more aggressive species over 15 cm. An angelfish, at about 15 cm, sits at that boundary. Our care guide plans more conservatively than OATA's floor, around roughly 200 litres, a 100 × 40 cm footprint and about 50 cm of usable height for an adult pair.

Groups need more. OATA suggests allowing 40 litres per adult fish when stocking shoaling species such as angelfish, and our care guide asks for substantially more space, visual barriers and a fallback plan for any group of adults.

A worked example

Suppose you have a 200 litre tank that is 50 cm tall. That matches our planning figure for a compatible adult pair, and every companion adds to the load. Five adult angelfish would use the whole 200 litres at OATA's allowance before a single companion is added, so a group of that size calls for a bigger aquarium and a second tank or rehoming route in case squabbles start. The larger the aquarium, the more stable its temperature and water quality will be, which OATA gives as a reason to buy as large as you reasonably can.

Set the water to a stable routine target

Keep the aquarium at 24–27°C, pH 6.5–8.0 and 5–12 dGH. These values are the overlap of FishBase's recorded range for the species and OATA's American cichlid guidance, which is a general guide for the whole group rather than a species-specific optimum. The same overlap is the routine target in our freshwater angelfish care guide.

Seriously Fish gives a lower pH ceiling than OATA, 7.4 rather than 8.0. Water at pH 6.5–7.4 falls inside every range in the table, so if your tap water already sits there, leave it alone. Wherever your water sits within the routine target, measure it and keep it steady rather than chasing an ideal number.

Values to hold at zero or low

• Ammonia and nitrite: zero.
• Nitrate: no more than 20 mg per litre above your normal tap water level, as OATA advises.
• Carbonate hardness: OATA gives 3–10 dKH for American cichlids.

Measure before you change anything

Tap water differs from one home to the next, so avoid fixed recipes for mixing tap and RO water. Measure GH, KH and pH first, and keep any deliberate change gradual. If those terms are new to you, our guide to which water values to test and why explains each one, and the water parameter matcher lets you compare your measured readings with stated guidance before you decide. For this fish, the routine target above is the range to aim for.

Mature the filter, then add gentle flow and steady heat

The RSPCA calls filters vital: fish release toxic ammonia, and a working biological filter grows beneficial bacteria that convert it to nitrite, also toxic, and then to nitrate, which is safer. OATA adds that those bacteria must increase every time more fish are added and feeding goes up. Overstocking, or stocking too quickly, causes new tank syndrome, with ammonia and nitrite rising to levels that can make fish ill or kill them.

Confirm zero ammonia and zero nitrite with a test kit before any angelfish goes in, because a calendar cannot tell you a tank is ready. If this is your first aquarium, follow our step-by-step guide to setting up and maturing a first tropical tank before you order, and add fish gradually afterwards.

Filtration and flow

Seriously Fish notes that angelfish prefer gentle water flow. For a tank of about 200 litres it suggests a turnover of four to five times the volume an hour, which means a filter rated at 800–1000 litres per hour. Gentle flow still means well-oxygenated water, never stagnant water, so choose filtration that keeps the water clean without making the fish fight a harsh current. Cover any intake an angelfish or its fins could be drawn against.

Heating

To hold 24–30°C in a tank of that size, Seriously Fish estimates roughly 200–275 W of heating, assuming a room of around 20°C. Check the actual temperature with a thermometer rather than trusting the heater dial, and aim for the 24–27°C routine target.

Substrate

OATA recommends fine aquarium gravel or sand for American cichlids, as many species will dig or sift the substrate when feeding or breeding. Anchor decor so digging cannot shift it.

Build a planted, vertical layout with a secure lid

Seriously Fish recommends a well-planted tank with tall, leafy plants such as Amazon swords, which echoes the densely vegetated swamps and flooded ground where FishBase records wild adults. Plants, roots and upright wood make good layout inspiration; no single plant or substrate colour is essential.

Structure with open water

• Use vertical plants or wood to break sight lines, so one fish cannot watch and chase another across the whole tank.
• Keep areas of open water where an adult can turn without dragging its long fins.
• Avoid sharp edges near the swimming space, to protect the long fins.
• Expect broad leaves and smooth vertical surfaces to become spawning sites if a pair forms.

Fit a secure lid

Our care guide advises a secure lid with access left for maintenance. If an angelfish ever jumps out, return it to aquarium water straight away using wet hands or a wet soft net, keep handling to a minimum, and watch its breathing, balance and any visible injury over the following hours. Then check the lid for the gap it found.

A layout built this way gives each fish somewhere to retreat, lets a pair claim a spot without controlling the whole tank, and keeps the fins that make angelfish so striking in good condition.

Feed a complete staple with frozen variety

Seriously Fish describes the species as omnivorous, but notes that wild fish feed predominantly on small crustaceans and other aquatic invertebrates from the riverbed. In the aquarium it accepts pellet or flake food and relishes live or frozen foods. OATA's advice for American cichlids points the same way: they are generally omnivorous but often prefer meaty foods.

How much and how often

OATA advises feeding American cichlids only what they can eat within a few minutes, once a day, and warns that they can eat large amounts in one sitting, so take care not to overfeed. Excess food and faeces break down and release toxic waste into the water. A controlled feeding study on freshwater angelfish supports the idea that feed composition matters, though it sets no single household menu.

Make sure every fish eats

In a pair or group, one fish can take more than its share. Watch each angelfish at feeding time, spread food so a subordinate fish can reach some, remove anything left uneaten, and keep an eye on body profile over the weeks. A fish that thins while its tankmates stay rounded is probably being crowded out and may need a change of layout or companions.

Keep a weekly testing and water-change routine

OATA strongly recommends a 25% partial water change at least once every week, with a siphon to lift solid waste from the gravel, and regular testing, at least once per week, so ammonia and nitrite never build up. In a 200 litre aquarium that is 50 litres a week. Treat that as a starting routine: our care guide points out that test results, stocking, feeding, plant growth and filter performance decide how often water really needs changing, so adjust from measured conditions rather than waiting for cloudy water.

Weekly sequence

1. Test ammonia, nitrite and nitrate, and record the readings.
2. Check temperature with a thermometer against 24–27°C.
3. Siphon out a quarter of the water along with waste from the gravel.
4. Treat the replacement water with tap water conditioner to remove chlorine or chloramine.
5. Check the filter for blockages, rinsing media only in the water you removed.
6. Refill with conditioned water close to the tank temperature, avoiding an abrupt swing.

Why the filter never goes under the tap

Do not run filter media under the tap, because any chlorine or chloramine present may kill the bacteria established in it. Rinse it lightly in the tank water removed during the change instead, so fewer bacteria are lost. OATA stresses that good husbandry is essential, as American cichlids can be stressed by even the smallest amounts of ammonia.

On delivery day: film, float and release

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

Steps on the day

1. Be at the delivery address to receive the parcel, as live fish cannot be left unattended.
2. Start filming before the parcel is opened: one continuous video showing it still sealed with the outer box visible, you opening it, and the fish still inside the sealed bag. Film every delivery like this.
3. Open and inspect the parcel on 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 WhatsApp for the fastest reply, with your order number and the unboxing video, and we will arrange a replacement or refund.

For the Live Arrival Guarantee, someone must have been at the address to receive the parcel, it must be opened and inspected the same day it arrives, and the continuous unboxing video must show it still sealed. The video also makes claims quicker and fairer, because our courier may request it when we raise one.

Tank checks before the fish goes in

OATA advises checking that ammonia and nitrite are zero before adding any fish, so test on the morning of delivery rather than with the bag already floating. Once released, a healthy angelfish shows steady swimming, regular breathing, clear eyes, open and undamaged fins, a normal body profile and, within a short time, consistent feeding.

When something looks wrong, test first

OATA recommends watching for changes rather than waiting for a crisis. Each fish varies a little, but these shifts are worth acting on.

What to do, in order

1. Test ammonia, nitrite, nitrate, temperature and, where relevant, pH straight away.
2. Treat any detectable ammonia or nitrite as urgent, and avoid sudden elective swings in pH, hardness or temperature.
3. Separate an affected fish only if a mature, suitable second tank is ready.
4. Photograph the signs, note when they started, then contact us or a fish vet.
5. Use only a lawful product labelled for the species and system, following its instructions or a vet's direction.

The first weeks after arrival

A new angelfish may take a little while to feed confidently in a strange tank, so offer small amounts and remove what it leaves. Keep testing through the first weeks, because OATA explains that the filter bacteria have to catch up with every fish added, and hold back on adding further fish until ammonia and nitrite stay at zero.

White spots, head lesions or unusual droppings are signs to record and escalate rather than proof of one cause, and there is no safe universal heat-raising recipe for white spot. Fasting, peas or medicated food are no substitute for a diagnosis. The RSPCA's fish health advice likewise puts water quality and visible signs first.

Pairs, groups and why one angelfish alone is not the default

OATA says angelfish are social and should be kept in groups or as a pair at minimum, and that fish kept singly may become stressed. FishBase suggests aquarium groups of five or more individuals, with pairs kept in smaller tanks for breeding. Seriously Fish calls the species generally peaceful but notes that it may squabble with its own kind, and reminds keepers that angelfish are still cichlids, so some aggression should be expected from time to time.

Choosing between a pair and a group

• A compatible pair is a workable adult plan, but two fish chosen at random may fight rather than pair.
• A group of young fish lets a pair form naturally, though social rank affects who feeds and who is chased, so more fish is not automatically calmer.
• A group of adults needs substantially more space, visual barriers and close observation, plus a second tank or rehoming route ready before conflict starts.

No single number suits every tank. Watch feeding access, fin condition, hiding, chasing and how each fish uses the space; a fish that is persistently shut out needs a change, not patience.

When a pair starts breeding

Angelfish spawn on vertical surfaces such as slate, broad-leaved plants or even the aquarium glass, and both parents may guard the eggs and young. Breeding sharpens territorial defence, so tank mates can be chased hard. Keep the adults well fed, as Seriously Fish notes they have been known to eat their fry. A behavioural study summarised in our care guide supports pair choice and serial monogamy, meaning a pair can change rather than mate for life. If you want to raise young, a dedicated, mature breeding tank is safer than a busy community.

Choosing companions by size, fins and feeding speed

OATA says calmer American cichlids such as angelfish can be mixed in a robust community aquarium with larger shoaling species, while the more aggressive cichlids must be kept alone or with equally aggressive cichlids. Seriously Fish rates the angelfish a good community fish but warns that it may eat small fish such as tetras. Before buying companions, ask us with your tank size and current stock, and we will go through the list with you.

Bottom dwellers and invertebrates

Corydoras and bristlenose plecos are often considered because they use a different level of the aquarium, but their adult size, the floor space available and their water needs still decide whether they fit. Very small tetras, shrimp and fry remain at risk of being eaten.

Signs a mix is not working

• Ragged or split fins on the angelfish, pointing to a companion that nips.
• An angelfish hanging back at feeding time while faster fish take the food.
• One fish chasing another constantly, or a fish hiding most of the day.
• Small companions disappearing as the angelfish grows.

Any of these calls for a change, whether that means rearranging the layout, moving a fish to a second tank or rehoming it, rather than waiting for the problem to settle on its own.

Fish to leave out

Leave out prey-sized fish, persistent fin-nippers and highly aggressive cichlids. A robust community of larger, calm shoaling fish that share the 24–27°C routine target is the combination OATA describes.

Questions keepers ask about angelfish

How big does a blue angelfish get?

Plan for an adult of about 15 cm in length. Seriously Fish records 150 mm standard length for Pterophyllum scalare, and the long dorsal and anal fins can make an adult roughly 20–25 cm tall, so choose a tank at least 50 cm high as well as long enough.

What size aquarium do angelfish need?

Seriously Fish gives an aquarium of 100 × 40 × 50 cm, about 200 litres, as the smallest to consider for Pterophyllum scalare. OATA treats 120 litres as the floor for a pair of smaller American cichlids and allows 40 litres per adult angelfish when stocking, so a group needs more room than a pair.

How many angelfish should I keep together?

Keep at least a compatible pair rather than one fish alone. OATA advises a pair at minimum and warns that a single angelfish may become stressed, and FishBase suggests aquarium groups of five or more for Pterophyllum scalare, which need substantially more space and a plan for squabbles.

Is a freshwater angelfish suitable for beginners?

Our care guide rates it intermediate: manageable for a prepared keeper, but no shortcut around aquarium basics. You need a fully cycled, tall aquarium of about 200 litres, weekly testing and water changes, and a plan for companions and any aggression.

What do angelfish eat?

Feed a complete cichlid pellet, granule or suitable flake as the staple, with frozen or freeze-dried foods such as daphnia, brine shrimp or bloodworm for variety. Wild Pterophyllum scalare feed mainly on small crustaceans and other aquatic invertebrates. OATA advises feeding only what they can eat within a few minutes, once a day.

What temperature and pH do angelfish need?

Keep them at 24–27°C, pH 6.5–8.0 and 5–12 dGH. That is the overlap of FishBase's recorded range and OATA's general guidance for American cichlids, used as the routine target in our care guide. Hold the values steady and keep ammonia and nitrite at zero.

Are angelfish aggressive, and do they nip fins?

Pterophyllum scalare is generally peaceful but is still a cichlid: Seriously Fish notes that it may squabble with its own kind, and pairs defend their space more strongly when breeding. Its own long fins are the ones at risk in a community, so keep it away from persistent fin-nippers.

Which fish can live with angelfish?

OATA says calmer cichlids such as angelfish can be mixed in a robust community with larger shoaling species. Leave out fish small enough to swallow, because angelfish may eat small fish such as tetras, and treat shrimp and fry as at risk. Corydoras and bristlenose plecos are often considered because they use lower levels, but check their adult size, floor space and water needs first.

How will my angelfish arrive alive in the UK?

Start filming before the parcel is opened: one continuous video showing the sealed box, the opening and the fish still inside its sealed bag. Your Pterophyllum scalare 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, message us the same day with your order number and the video for a replacement or refund.

Sources for this care guide

• FishBase: Pterophyllum scalare, for family, distribution, wild habitat, recorded environmental range, length records, aquarium grouping note and IUCN status.
• Eschmeyer's Catalog of Fishes, for the accepted name, authorship and type locality.
• Seriously Fish: Pterophyllum scalare, for tank size and height, water profile, flow, heating, diet, behaviour, sexing and breeding behaviour.
• OATA: How to look after American cichlids, for group guidance on water, space, social needs, feeding, maintenance, introduction, health signs and compatibility.
• RSPCA: fish environment, for filtration and the nitrogen cycle.
• RSPCA: fish health and welfare, for visible health signs.
• Kasiri, Farahi and Sudagar (2012), a controlled feeding study on freshwater angelfish.
• Tropical Fish Co freshwater angelfish care guide and delivery page, both linked above, for store planning figures and arrival steps.