Marble Angelfish (Pterophyllum scalare)

Choose the marble form for a tall, mature aquarium

Marble Angelfish is a domestic colour form of Pterophyllum scalare, a tall freshwater cichlid from the Amazon basin in South America that reaches 15 cm. It suits an intermediate keeper prepared to provide a mature, spacious aquarium and manage changing social behaviour. The accepted species name remains Pterophyllum scalare, in the family Cichlidae.

The native range covers parts of Brazil, Colombia, French Guiana, Guyana and Peru. FishBase records adults in densely vegetated swamps and flooded ground with clear or silty water, giving useful inspiration for tall plants, roots and sheltered areas. Aquarium care should still be planned around measured water, adult dimensions and the behaviour of the fish in front of you.

Match the fish to the aquarium and keeper

Make the adult plan before choosing a dispatch size

Plan around a recorded maximum of 15 cm total length. Extended fins can make an adult roughly 20–25 cm tall, so upward growth is the decisive feature. A shallow aquarium can hold a respectable nominal volume while still restricting the dorsal and anal fins or leaving too little vertical turning room.

For a compatible adult pair, plan roughly 200 litres, about a 100 × 40 cm footprint and 50 cm usable height. Use routine water of 24–27°C, pH 6.5–8.0 and about 5–12 dGH. Our complete freshwater angelfish care guide explains the adult planning policy in greater depth.

Select a dispatch size without mistaking it for adult size

One purchase supplies one Marble Angelfish in the size chosen on the live selector. The size you select is the size supplied, not the adult size. Use the selector itself when choosing between the named grades, then keep the 15 cm adult-length and 20–25 cm overall-height plan separate from that choice.

Smaller grades still need a complete adult aquarium plan. Do not build a temporary setup around the fish’s first measurement unless a larger, cycled aquarium is already prepared for the next stage. The filter, social group and tank mates must also be chosen for the eventual biomass and territorial behaviour rather than the dispatch grade alone.

Sex is guaranteed only when the selected option explicitly states male or female. This Marble Angelfish listing has no sex-guaranteed option.

The gallery images are representative of this type of animal rather than photographs of the exact animal supplied, so colours can look slightly different from the live animal.

The gallery scene shows two gold and silver angelfish with pale blue patches, fine reddish speckles and long trailing fins. Its pair of visible fish does not alter the one-animal purchase unit. Treat the image as a guide to angelfish body shape and finnage rather than an exact marble-pattern promise.

Build the aquarium around adult height and turning room

Seriously Fish recommends an aquarium measuring 100 × 40 × 50 cm, approximately 200 litres, as the smallest species-focused plan. That gives an adult pair useful horizontal territory as well as the vertical room needed by the extended dorsal and anal fins. Measure usable water height after allowing for substrate, the waterline and any equipment that occupies the swimming area.

OATA’s American-cichlid guidance is broad group guidance: it gives at least 120 litres for a pair of smaller American cichlids, says adult angelfish need a sufficiently tall aquarium and suggests allowing 40 litres per adult when stocking them. We use the more conservative 200-litre, 100 × 40 cm and 50 cm usable-height plan for a compatible adult pair.

Use dimensions before nominal litres

• For a compatible pair: begin with roughly 200 litres and the stated footprint and height, then account for decor and other inhabitants.
• For a group: provide substantially more room, several broken sight lines and a mature separation plan. Multiplying 40 litres by five reaches 200 litres, but that arithmetic does not create five territories inside a pair-sized footprint.
• For a community: reserve space for every companion’s adult body size, social group and feeding area rather than allocating the full volume to the angelfish.

Aquarium shape can defeat a litre figure. A long but shallow tank may offer swimming distance without safe fin clearance, while a tall but narrow tank may prevent an adult from turning comfortably. Keep open routes through the middle of the aquarium and avoid filling every vertical plane with wood or plants.

Check the usable space rather than the box dimensions

A tank sold as 50 cm tall may offer less usable water height after adding substrate and leaving space below the rim. Measure from the top of the substrate to the normal waterline, then check whether wood, filter pipes or dense planting narrow the routes an adult would use. For example, a 5 cm substrate bed in a tank holding water to 3 cm below the rim removes 8 cm from the stated height before decor is considered. Rework the layout if long fins would have to brush the substrate, surface or ornaments during a normal turn.

Plan a compatible pair or a deliberately managed group

Angelfish are social cichlids, but social does not mean that any two individuals will form a peaceful pair. The species entry advises groups of five or more, while UK group guidance treats a pair or group as the minimum social plan and warns that a fish kept alone may become stressed. A compatible pair and two fish selected at random are different arrangements.

A juvenile group can allow pair formation and normal social choice. As the fish mature, hierarchy, feeding access and preferred territories may change. A forming pair can claim a broad leaf, piece of wood, aquarium wall or another vertical surface, then drive lower-ranking fish away from food or shelter. More fish therefore requires more space, not simply more hiding places inside the same pair-sized tank.

Check the group at three levels

Do not rely on a single quiet day as proof of long-term compatibility. Observe during feeding, after maintenance and when the lights follow their normal cycle, because competition may appear only around a valued area or meal. A workable group plan includes a second suitable aquarium or a realistic rehoming route before conflict begins.

Review the social plan through the first month

During the first week, record which fish reaches each feeding point and which areas each one uses. Repeat the check after decor is moved, after a water change and whenever two fish begin spending time together near a vertical surface. At the end of the first month, compare fin condition, body profile and feeding access with the first-week observations. A fish that is consistently excluded needs action even if no dramatic fight occurs, because repeated missed meals and restricted movement can develop gradually.

Set stable water within the overlapping care range

Use 24–27°C, pH 6.5–8.0 and approximately 5–12 dGH as the routine aquarium target. This deliberately overlaps the species range of 24–30°C, pH 6.0–8.0 and 5–13 dGH with the American-cichlid range of 22–27°C, pH 6.5–8.0 and 4–12 dGH. Stability inside the routine range matters more than repeatedly chasing a single ideal reading.

Measure temperature with a thermometer instead of relying only on the heater dial. Test pH and hardness before altering the source water, particularly when moving a fish between aquariums or introducing it after transport. Our water chemistry guide explains GH, KH and pH, while the water matcher helps compare measured aquarium values with the stated range.

Turn test results into decisions

Avoid copying fixed tap-water and reverse-osmosis recipes. Different water supplies begin with different GH, KH and pH, so the same mixing ratio can produce a different result. Define the measured starting point, the target and the reason for changing it, then make any elective adjustment gradually.

Separate stability from false precision

If the aquarium reads 26°C, pH 7.2 and 9 dGH on repeated tests, those values already sit inside the routine range; changing them to 25°C, pH 7.0 and 8 dGH adds disturbance without solving a care problem. When two tests disagree, repeat them with clean equipment before altering the aquarium. Record readings alongside water changes, feeding changes and filter maintenance so an unexpected movement can be connected to a practical cause rather than answered with several additives at once.

Establish biological filtration before the fish arrives

A working biological filter is essential. The RSPCA explains that fish release toxic ammonia, which filter bacteria convert first to nitrite and then to the safer nitrate. An elapsed number of weeks cannot show that this process is functioning; measured ammonia and nitrite must both be zero before adding the angelfish.

Prepare and mature the aquarium before choosing livestock. The first tropical aquarium guide sets out the practical sequence for installing equipment, establishing the filter and checking water. Add fish gradually because every increase in feeding and waste requires the bacterial population to support a larger load.

Use these filtration checkpoints

Keep nitrate from rising unchecked through measured feeding, regular testing and partial water changes. The American-cichlid target is no more than 20 mg per litre above the normal tap-water level. Record the tap and aquarium readings separately so a change in the incoming water is not mistaken for a filtration failure.

Watch the filter after each increase in load

Test after adding fish and after any clear increase in feeding rather than assuming yesterday’s result covers the new load. If ammonia or nitrite becomes detectable, respond as a water-quality emergency and reduce further pressure on the system while the cause is addressed. Do not add more livestock during that period. Once readings return to zero, continue checking until repeated results show that the biological filter is handling the revised load. A filter that worked for a small juvenile setup still needs enough capacity and maintenance access for the adult aquarium.

Arrange vertical cover and make the introduction gradual

Use tall plants, broad leaves or smooth wood to create vertical structure, then preserve open water where an adult can turn without dragging its fins. Broken sight lines allow a lower-ranking fish to move out of direct view, while several routes through the aquarium reduce the chance that one territory blocks every feeding or resting area.

Choose smooth, stable decor. Sharp edges can damage extended fins, and digging or substrate sifting can loosen unsecured pieces. Fine aquarium gravel or sand suits the group guidance. Live plants may be disturbed, so secure roots well and use the layout for cover rather than depending on one delicate planting scheme.

Provide gentle distributed flow without allowing stagnant areas. Watch how the fish holds position: steady swimming through open water is preferable to continual effort against one powerful outlet. Keep a secure lid, protect filter intakes and leave enough access to remove waste and inspect equipment.

Use a first-week checklist

1. Before transfer, confirm the aquarium is mature, temperature is steady, and ammonia and nitrite are zero.
2. Compare the established holding conditions with the aquarium and make the transition gradual, avoiding abrupt temperature, pH or hardness changes.
3. After introduction, check upright posture, regular breathing, open fins and movement through more than one part of the tank.
4. At each meal, confirm that the new fish swallows food rather than merely approaching it.
5. Inspect the body and fins daily for wounds, white spots, fluffy growths, clamping or a sudden colour change.

Follow the arrival sequence

1. Have someone present to receive the parcel because live fish cannot be left unattended.
2. Start filming every delivery while the parcel is still sealed and the outer box is visible.
3. Open the parcel the same day in one continuous take, showing the fish still inside the sealed bag before anything is disturbed.
4. Float the bag for 20–30 minutes before releasing the fish.
5. Never pour the bag water into the aquarium.

A separate quarantine aquarium must itself be mature, heated, filtered and suitably sized; separate equipment prevents water transfer between systems. Keep quarantine planning ready before the fish arrives rather than improvising an uncycled container after a problem appears. Read the delivery and Live Arrival Guarantee policy for the shop’s dispatch days and claim process.

Feed a complete staple and measured invertebrate variety

Freshwater angelfish are omnivorous. In nature they feed predominantly on zoobenthos, including small crustaceans and other aquatic invertebrates. In the aquarium, use a nutritionally complete cichlid pellet, granule or suitable flake as the staple, choosing a particle size the selected fish can swallow.

Add appropriate frozen or freeze-dried variety such as daphnia, brine shrimp or bloodworm. Live or frozen foods may also be accepted, but one attractive treat should not replace the complete staple. A controlled angelfish feeding study reinforces that feed composition affects growth and reproductive performance without creating one universal household menu.

Build each meal around access and restraint

Observe swallowing rather than judging the meal by how quickly the dominant fish reaches it. A subordinate animal can lose condition while food still disappears rapidly. Check body profile over time and make portion changes gradually, using feeding response and water-test results together.

Overfeeding increases faeces and leaves food to break down, adding toxic waste to the aquarium. Reduced appetite is also a health warning rather than a reason to scatter extra treats. If a fish suddenly stops eating, test the water and assess breathing, swimming, injuries and social pressure before changing the diet.

Adjust one part of the meal at a time

If food remains after a few minutes, remove it and offer less at the next daily feed rather than skipping observation or changing several foods together. When one fish takes every pellet, divide the same measured portion between separated feeding points and confirm that the lower-ranking fish swallows its share. If the complete staple is refused but an attractive supplement is taken, do not let treats become the whole menu; first check water quality, particle size, social pressure and the fish’s condition.

Maintain the aquarium weekly and respond to changes early

Use a 25% partial water change at least once a week as the starting routine. Siphon accumulated solid waste, treat replacement tap water with conditioner to remove chlorine or chloramine and avoid abrupt temperature or chemistry changes. Adjust the routine from measured nitrate, stocking, feeding and filter performance rather than waiting for cloudy water.

Combine maintenance with observation

• Test ammonia and nitrite at least weekly and whenever behaviour or feeding changes.
• Record nitrate and compare it with the normal tap-water value.
• Check the filter for blockages, unusual noise or reduced output.
• Inspect the heater and confirm temperature with a separate thermometer.
• Look along the fins and body for damage, spots, growths, ulcers or missing scales.
• Watch every fish feed so social exclusion is noticed before obvious weight loss.

Healthy fish usually show steady swimming, regular breathing, clear eyes, open undamaged fins, an appropriate body profile and consistent feeding. The RSPCA fish-health guidance supports using visible changes and water checks to identify a developing welfare problem early.

If you see gasping, erratic swimming, unusual balance, clamped fins, white spots, wounds, rapid breathing or a sudden appetite change, test ammonia, nitrite, nitrate and temperature immediately. Check pH where a chemistry shift is possible. Isolate an affected fish only when the separate aquarium is mature and suitable; an improvised container can add water-quality stress.

Seek prompt help from a specialist aquatic retailer or fish vet when signs persist or injury is present. Use only lawful treatments labelled for the animal and aquarium system, following the product instructions or veterinary direction. Avoid preventive medication and fixed heat recipes because similar visible signs can have different causes.

Use the monthly record to refine the routine

Compare four weekly sets of readings rather than treating each result in isolation. If nitrate rises faster each week while ammonia and nitrite remain zero, review feeding, waste removal, stocking and the timing of water changes. If reduced filter output follows media maintenance, inspect for displaced media or a blockage before altering water chemistry. A repeated log also shows whether appetite, aggression or fin damage changed at the same time as a maintenance event, making the next response more focused.

Screen every proposed companion before mixing species

Marble Angelfish can live in a robust community, but compatibility remains conditional. They are cichlids that may defend territory, swallow very small fish or lose feeding access beside much faster species. No companion is universally safe because adult size, aquarium dimensions, hierarchy and individual behaviour can change the result.

Use conditional categories, not a guaranteed list

• Potentially suitable: calm, robust, larger shoaling fish with overlapping water needs, enough group space and fair feeding access.
• Use caution: other angelfish and territorial cichlids. Provide visual barriers and a prepared separation route.
• Avoid: very small prey-sized fish, persistent fin-nippers, highly aggressive species, much faster-feeding species and cold-water fish whose temperature needs do not overlap.

Assess the exact adult species rather than relying on a broad common name. Floor-dwelling and mid-water fish may still compete during feeding or occupy the same defended area. Likewise, a peaceful label cannot resolve incompatible temperature or social-group needs.

If you are comparing colour forms in the angelfish collection, apply the same adult-space and behaviour screen to each fish. A different colour does not turn Pterophyllum scalare into a different compatibility category.

Work through the whole community, not one pairing

A proposed companion may pass the size and water checks yet still fail when its full social group is added. Count the territory, swimming room and feeding access required by all inhabitants at adult size. Then consider the angelfish pair’s potential breeding area. If either species depends on the same central space or one group cannot feed without entering defended territory, change the stocking plan before combining them.

Manage hierarchy and breeding territory before injuries develop

Angelfish may swim calmly for long periods and still become territorial around a preferred area. Brief displays and short pursuits can occur within a hierarchy. Repeated cornering, blocked access to food, torn fins, persistent hiding or declining body condition show that the arrangement needs intervention.

A compatible pair may clean and lay eggs on a broad leaf, slate, wood, filter housing or aquarium glass. Both parents may guard the eggs and young, expanding the defended area into space previously used by community fish. Breeding behaviour therefore changes the compatibility calculation even when the aquarium was settled beforehand.

Match the response to what you see

Two randomly selected fish are not automatically compatible, and adding another angelfish does not reliably redirect aggression. More individuals may create additional competition unless the aquarium has substantially more territory and several visual breaks.

Keep the alternative aquarium heated, filtered and biologically mature. Moving a bullied fish into poor water replaces one welfare problem with another. When separation is required, maintain stable temperature and chemistry and minimise chasing or handling.

Answer the key questions before choosing your fish

How big does a Marble Angelfish get?

It reaches 15 cm, and its extended fins can make it roughly 20–25 cm tall, so plan the aquarium around adult length and vertical clearance.

What size aquarium does Pterophyllum scalare need?

Plan roughly 200 litres, a 100 × 40 cm footprint and about 50 cm usable height for a compatible adult pair, with substantially more room for a group or community.

How many Marble Angelfish should I keep together?

FishBase recommends groups of five or more, while OATA advises a pair or group at minimum and warns that an isolated fish may become stressed; a group needs substantially more space, visual barriers and a separation plan.

Is a Marble Angelfish suitable for beginners?

It has an intermediate store care rating and suits a prepared keeper with a mature, sufficiently large and tall aquarium, measured water values and a plan for territorial behaviour.

What does Pterophyllum scalare eat?

Feed a complete cichlid pellet, granule or suitable flake once daily, offering only what it can eat within a few minutes and adding measured frozen or freeze-dried daphnia, brine shrimp or bloodworm for variety.

What temperature and pH does it need?

Use 24–27°C, pH 6.5–8.0 and about 5–12 dGH, the routine overlap of FishBase species values and OATA American-cichlid group guidance, with zero ammonia and zero nitrite.

Is this fish aggressive or likely to nip fins?

Expect occasional squabbling, territorial chasing and stronger defence around breeding sites; persistent fin-nippers should be avoided because they can damage its extended fins.

Which kinds of fish can it live with?

Consider calm, robust, larger shoaling fish with overlapping water needs and fair feeding access; avoid very small fish, persistent fin-nippers, highly aggressive species, much faster-feeding species and incompatible cold-water fish.

How does this fish arrive alive in the UK?

Have someone present to receive the parcel. Start filming every delivery continuously from the sealed parcel, show it being opened with the fish still inside the sealed bag, float the bag for 20–30 minutes, and never pour the bag water into the aquarium.

Read the scientific and welfare bibliography

• FishBase: Pterophyllum scalare — identity, family, distribution, habitat, environmental range, size and social note.
• Seriously Fish: Pterophyllum scalare — aquarium dimensions, water, diet, behaviour and breeding biology.
• OATA: How to look after American cichlids — UK group guidance for water, maintenance, feeding, social care and compatibility.
• RSPCA: Aquarium environment — biological filtration and waste conversion.
• Eschmeyer’s Catalog of Fishes — accepted name, authorship, family placement and distribution.
• Kasiri, Farahi and Sudagar — controlled study of feed types in freshwater angelfish.
• RSPCA: Fish health and welfare — visible health signs and water-quality-first response.