Red-Backed Paradise Fish (Macropodus erythropterus)

Recognise the red-backed paradise fish

The Red-Backed Paradise Fish, Macropodus erythropterus, is a freshwater member of the Osphronemidae family, which contains gouramis and paradise fish. FishBase places the species in Viet Nam and records a maximum length of 6.5 cm standard length. It suits keepers who can provide a mature, filtered aquarium, test the water regularly and plan companions around its breeding-related change in behaviour.

This is a labyrinth fish. Members of its family possess a specialised organ that allows them to breathe atmospheric air as well as using their gills. That ability does not reduce the need for filtration, clean water or thoughtful stocking.

Look for the defining pattern

The species profile describes a forked tail, reddish predorsal and subdorsal areas, red markings in the dorsal and caudal fins, and darker margins on the scales of the head and body. It is frequently confused with the similar Macropodus spechti, so identity should rest on the complete combination of features rather than red colour alone.

Keepers comparing related fish can browse our gouramis and labyrinth fish collection, but compare adult dimensions, water ranges and temperament individually rather than assuming every family member needs the same aquarium.

Understand the animal and adult planning size

One purchase supplies one Red-Backed Paradise Fish. Plan the aquarium around its adult dimensions rather than its size at purchase.

FishBase records a maximum of 6.5 cm standard length for male or unsexed fish. Seriously Fish uses a larger 8 cm standard-length planning reference. Use the 6.5 cm recorded adult size consistently while allowing for the larger planning reference when arranging space and decor.

Do not infer sex from size or photographs

Sex is guaranteed only when the selected option explicitly states male or female. This Red-Backed Paradise Fish listing has no sex-guaranteed option.

Mature males are described as larger than females and as having extended soft rays in the dorsal, anal and caudal fins. Those traits may help with observation after development, but neither the animal’s size nor a representative image changes the offer disclosure above.

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.

Prepare the aquarium before delivery

Read our delivery and Live Arrival Guarantee policy for the applicable packing, receipt, acclimatisation and claim instructions. Complete the filtered, tested aquarium before arranging delivery so the fish can enter a prepared home.

Plan around the decisive care numbers

Seriously Fish gives the species an aquarium range of 20–30°C, pH 6.0–8.0 and 5–20 dGH. Its minimum for a single pair is an 80 × 30 cm base or equivalent, equating to about 72 litres. Treat the footprint as the primary spatial test because a taller aquarium with a narrow base does not provide the same horizontal area.

For this one-animal purchase, using the same 80 × 30 cm footprint is a prudent way to avoid designing only around the fish’s size on arrival. A pair reaches the stated minimum; a group or mixed community needs additional space determined by the number, adult sizes, behaviour and territory use of every resident.

Choose a stable point inside all residents’ overlapping ranges rather than chasing the middle of a range by repeatedly altering the water. Measure the aquarium’s actual pH, hardness and temperature before making the stocking decision.

Build cover without sacrificing swimming space

Start with the 80 × 30 cm base used for a single pair and arrange the aquarium so the fish can move between open water and sheltered areas. The species can be maintained in a fully decorated aquarium, although some breeders use no substrate to simplify maintenance. For a display aquarium, the important choice is whether the whole layout remains cleanable and provides useful cover.

Create shaded areas

Driftwood roots and branches can be positioned to form several shady spots. Use them to divide the aquarium visually without filling every swimming route. A fish moving away from another resident should be able to pass behind decor rather than reaching a dead end. Keep all wood stable so routine maintenance does not disturb the entire structure.

Floating or surface vegetation has a clear role when breeding is intended because the male tends to place a bubble nest within a raft of plants. It can also supply overhead structure in the main display. Leave accessible surface areas between plant rafts because labyrinth fish breathe atmospheric air.

Use leaf litter deliberately

Dried leaf litter can strengthen the natural appearance, add cover and support microbe colonies that may become an early food resource for fry. Add it only where it can be inspected and removed during maintenance. Leaf litter is an optional design feature, not a replacement for filtration, testing or waste removal.

• Keep: an open route across the 80 cm length.
• Add: branches or roots that create several shaded retreats.
• Include: surface vegetation when planning breeding behaviour.
• Preserve: unobstructed access to atmospheric air.
• Check: that every decorated area remains reachable with a siphon.

Review the layout whenever fish are added or breeding behaviour begins. More animals increase the need for separation space, and the minimum for a single pair should not be treated as a group allowance.

Hold water inside the species range

Keep the aquarium within 20–30°C, pH 6.0–8.0 and 5–20 dGH. Those are the aquarium values published for Macropodus erythropterus. Test the water you actually have, then select companions whose requirements overlap without forcing repeated chemical adjustments.

Choose stability before a precise midpoint

The range does not require a target of exactly 25°C, pH 7.0 or 12.5 dGH. A stable value within the range is the practical goal. Use our water chemistry guide to understand what pH and hardness measurements mean, then compare your readings with the stated range using the aquarium water matcher.

A heater estimate must be tied to aquarium volume and room temperature. For a tank of about 72 litres, the species profile estimates roughly 75–100 W to maintain 20–30°C when the room is around 20°C. Treat that as a worked example, not a universal heater rating: aquarium shape, room conditions and the chosen temperature affect the equipment decision.

Record the normal readings before introduction. Later measurements then have a meaningful baseline, allowing you to recognise a change rather than reacting to a single number without context. When different residents need different ends of the range, choose the shared overlap or revise the stocking plan.

Match filtration to volume and waste

Use a well-established biological filter at all times. The RSPCA explains that beneficial filter bacteria process toxic ammonia into nitrite and then nitrate. A labyrinth organ permits atmospheric breathing, but it does not process dissolved fish waste or make an unfiltered aquarium suitable.

Size the filter from the real aquarium

At about 72 litres, the species profile uses a turnover of four to five times the aquarium volume each hour. That produces a worked filter rating of roughly 290–360 litres per hour. Check the manufacturer’s rating against the completed aquarium, then inspect the filter for blockages because restricted media or intakes reduce effective flow.

A larger aquarium needs a rating calculated from its own volume. For example, the four-to-five-times rule means multiplying the aquarium’s litres by four and by five to create a comparison band. Do not reuse the 290–360 litres-per-hour example for a different volume.

Protect the biological filter

OATA’s gourami and paradise fish guidance gives broad targets of zero ammonia, zero nitrite and nitrate no more than 20 mg per litre above the normal tap-water level. It recommends a 25% partial water change at least once every week and testing at least once per week.

1. Test ammonia and nitrite before the water change.
2. Siphon solid waste while removing 25% of the water.
3. Treat replacement tap water for chlorine or chloramine before adding it.
4. Check the filter for restricted flow or blocked intakes.
5. If cleaning is needed, rinse media lightly in removed aquarium water rather than under the tap.
6. Retest whenever behaviour, breathing, appetite or appearance changes.

Chlorine or chloramine may kill part of the beneficial bacterial population if media is washed under tap water. Cleaning everything aggressively at the same time can therefore work against the biological process the filter is meant to maintain. Preserve the established media while removing blockages and accumulated solid waste.

Feed suitable small foods once each day

In nature, the species is considered likely to prey on insect larvae and similar small animals. In the aquarium, offer small live or frozen Daphnia, Artemia, white worm or grindal worm. Some high-quality dried products may also be accepted, including quality dried food, freeze-dried Artemia and freeze-dried Daphnia.

Build the routine around acceptance

OATA’s family guidance describes gouramis and paradise fish as omnivorous and recommends a good-quality flake, granule or pellet, supplemented with small live or frozen foods such as daphnia, small bloodworm or tubifex. Feed once a day and give only what the fish can finish within a few minutes.

Watch the meal rather than relying on a fixed pinch. Stop adding food when the fish has eaten the portion it can take within a few minutes. Remove uneaten material because decomposing food adds waste to the aquarium and increases the burden on the biological filter.

If dried food is refused, use one of the specifically described small live or frozen foods and continue observing body condition and appetite. A change from normal feeding response belongs in the health check, especially when it appears alongside altered breathing, colour, swimming or hiding.

Do not increase feeding simply because more fish have been introduced. Add livestock slowly so the beneficial bacterial population has time to respond as total feeding and waste rise. Test ammonia and nitrite after any meaningful increase in aquarium load.

Prepare the aquarium before introduction

Finish the aquarium, establish the biological filter and learn its normal test readings before the animal arrives. Our first tropical aquarium guide sets out the preparation and maturation sequence. The essential readiness test is functional filtration with ammonia and nitrite at zero, not the number of days the aquarium has contained water.

Before arranging delivery

• Confirm an 80 × 30 cm base or an equivalent footprint.
• Set temperature within 20–30°C and check it remains steady.
• Measure pH and general hardness against 6.0–8.0 and 5–20 dGH.
• Test ammonia and nitrite and require zero readings.
• Check the filter for normal flow and unobstructed intakes.
• Leave accessible surface areas around floating vegetation.

First-week checkpoints

Observe swimming, breathing, colour, appetite and use of cover. Compare each observation with the animal’s developing normal pattern rather than expecting constant display. Test the water promptly if the fish hangs at the surface differently from its usual atmospheric breaths, sits on the bottom, swims erratically, hides more, changes colour or loses interest in food.

Keep the stocking increase modest. Beneficial filter bacteria need to respond whenever more fish are added and feeding rises. Adding several animals quickly can produce new tank syndrome because waste production overtakes biological processing, allowing ammonia or nitrite to rise.

First-month checkpoints

Continue a 25% partial water change at least once every week, test ammonia and nitrite at least once per week, and inspect the filter for blockages. Record whether the fish accepts dried food or needs a greater proportion of the listed live and frozen foods. Inspect fins, scales, eyes and body condition while learning its usual behaviour.

Do not treat routine surface breathing as proof of poor oxygenation or good water quality. This family naturally uses atmospheric air, while ammonia, nitrite and accumulated waste still require testing, filtration and maintenance.

Respond to changes before they escalate

Healthy-fish assessment is a pattern of observations rather than a single colour or pose. Look for clear, bright eyes, undamaged fins, intact scales and the absence of ulcerations or bumps. Learn the individual’s normal appetite, swimming, breathing, hiding and colour so a change can be recognised early.

Pair each sign with an immediate action

Water testing comes first because even small amounts of ammonia or nitrite can stress gouramis and paradise fish. Confirm that the filter is operating, inspect for blockages and carry out the established maintenance response without washing biological media under tap water.

Disease treatment depends on the condition, water readings and the other animals in the aquarium. Do not select medication solely from a symptom name. If a health change persists after the immediate water and equipment checks, contact us for further guidance and provide the readings, aquarium volume, temperature, stocking details and a clear description of the change.

Treat breeding as a change in care

Macropodus erythropterus is a bubble nester. The male tends to build the nest within a raft of surface vegetation and displays with the elongated dorsal, anal and caudal fins once the nest is complete. The species is relatively peaceful unless breeding, so nest building is also a signal to reassess compatibility and available retreat space.

Prepare the air space as well as the water

Seriously Fish recommends the tightest-fitting cover possible for breeding because fry need a layer of warm, humid air while the labyrinth organ develops. This supports fry development but does not guarantee spawning.

Soft water with a slightly raised temperature may induce reproductive behaviour. Any adjustment must remain controlled, stay within the species’ 20–30°C aquarium range and account for the needs of every resident.

Decide whether the main aquarium can absorb the behaviour

• Provide a raft of surface vegetation if breeding is intended.
• Preserve access to warm, humid air beneath a tight cover.
• Watch whether breeding changes chasing or access to cover.
• Review the space used by every other fish before allowing the situation to continue.
• Keep water testing and filter maintenance consistent as feeding and biological load change.

The pair does not need to be separated before spawning, and females are usually tolerated while the male constructs and tends the nest. Observe the actual interaction and revise the arrangement if one fish cannot feed, rest or move away.

Choose pair or group plans deliberately

The species can be maintained as a pair or group, and a group may show interesting behavioural interactions. The published minimum of an 80 × 30 cm base and about 72 litres applies to a single pair, not to an unrestricted number of fish. A group therefore needs a larger plan based on the number of animals, their adult dimensions, filtration demand and the usable separation created by the layout.

Start from the purchase unit

Each purchase supplies one animal. Buying one does not create a pair, and adding another later should be treated as a new stocking decision. Review the adult size, available footprint and existing residents before increasing the number. Do not infer sex from size, colour or gallery imagery when attempting to form a pair.

Observe access to food, surface air, open water and sheltered areas. An arrangement is failing if one animal is repeatedly excluded from these essentials. Revising the stocking plan is more useful than assuming that pair or group tolerance guarantees equal behaviour from every individual.

When a future addition is being considered, compare the completed aquarium—not its nominal capacity alone—with the pair minimum and the needs of all existing livestock.

Screen every companion before mixing

For this species, the direct description is relatively peaceful unless breeding. That supports a conditional community assessment rather than a universal tank-mate list. The result remains individual and depends on the aquarium, the animals involved and whether breeding behaviour develops.

Apply the same screen to every proposed companion

OATA’s group-level advice for paradise fish says to choose robust tank mates and avoid timid species, small fish that could be eaten, and fish that may nip their fins. Use those exclusions alongside the exact species’ adult dimensions and water range.

Do not treat a family label such as gourami, paradise fish, tetra or catfish as a compatibility answer. Screen the exact adult size, temperament, feeding access and water needs of the proposed animal. Apply the same screening process to invertebrates rather than assuming a predictable outcome.

For a stocking and compatibility assessment, contact us with the aquarium’s dimensions and volume, measured temperature, pH and hardness, current residents and intended number of Red-Backed Paradise Fish. Those details permit a more useful decision than a generic list of names.

Answer common buyer questions

How big does the Red-Backed Paradise Fish get?

FishBase records a maximum of 6.5 cm standard length for male or unsexed Red-Backed Paradise Fish.

What size aquarium does Macropodus erythropterus need?

Seriously Fish advises an aquarium base of at least 80 × 30 cm or equivalent, about 72 litres, for a single pair of Macropodus erythropterus.

How many Red-Backed Paradise Fish should I keep together?

The Red-Backed Paradise Fish can be maintained as a pair or group, but the 80 × 30 cm and approximately 72-litre minimum applies only to one pair; a group needs more space.

Does this fish suit beginners?

Choose it only if you can provide a mature filtered aquarium, test water regularly, maintain the stated ranges and respond when breeding changes its behaviour.

What does the Red-Backed Paradise Fish eat?

Offer the Red-Backed Paradise Fish small live or frozen Daphnia, Artemia, white worm or grindal worm, with accepted high-quality dried food; feed once daily and only what it eats within a few minutes.

What temperature and pH does it need?

Keep it at 20–30°C, pH 6.0–8.0 and 5–20 dGH, the species aquarium values published by Seriously Fish.

Is Macropodus erythropterus aggressive or likely to nip fins?

Macropodus erythropterus is relatively peaceful unless breeding; avoid fin-nipping companions and reassess the arrangement if nesting changes its behaviour.

Which kinds of animals can live with it?

Consider robust fish whose adult size and water needs fit the aquarium; avoid timid species, small fish that could be eaten and fish that may nip its fins. Specific outcomes with invertebrates remain uncertain, so apply the same screening rule.

How does this fish arrive alive in the UK?

Start filming continuously while the parcel is still sealed, then record it being opened with the fish still inside the sealed bag. Someone must be present to receive it; float the bag for 20–30 minutes before releasing the fish, and never pour the bag water into the aquarium.

Check the care references

• FishBase: Macropodus erythropterus — scientific identity, family, distribution, environment and maximum recorded standard length.
• Seriously Fish: Macropodus erythropterus — aquarium dimensions, water range, filtration example, diet, behaviour, sexual dimorphism and reproduction.
• OATA: Gouramis and paradise fish — UK group guidance on maintenance, feeding, introduction, observation and compatibility.
• RSPCA: Aquarium environment and filters — general fish-welfare guidance on biological filtration and waste processing.