Paradise Fish blue red (Macropodus opercularis blue red)

Meet a historic labyrinth fish with a territorial side

The Paradise Fish blue red (Macropodus opercularis) is a freshwater labyrinth fish in the Osphronemidae family. Its native range extends from the Yangtze basin south through China, including Hainan, to Taiwan and northern Vietnam. Plan for an adult length of 8 cm standard length. It suits a keeper who can provide relatively cool water, an aquarium at least 80 cm long and a carefully screened social arrangement.

FishBase describes the wild species in lowland habitats ranging from structured river margins and backwaters to small streams, irrigation channels, paddy fields and ditches. It is an obligate air-breather and can use atmospheric oxygen through its specialised labyrinth organ. That ability does not replace filtration, water testing or routine maintenance in an aquarium.

The blue-red name identifies the colour strain in this offer. Seriously Fish includes red and blue forms among the selectively bred ornamental strains of M. opercularis. The species is also known as the Chinese fighting fish, paradise gourami and blue paradise fish, but Paradise Fish blue red is the clearest name for this particular animal.

Decide whether its character fits your aquarium

This is not a passive community fish. Males are territorially aggressive, especially during reproductive periods, and FishBase records that males fight one another. OATA describes Paradise Fish as semi-aggressive and usually best kept on their own. A community arrangement therefore needs more thought than simply matching temperature and aquarium volume.

The species also has a notable place in aquarium history. FishBase records it as the first ornamental fish brought to Europe after the goldfish, while Seriously Fish traces its arrival in France to 1869. That history is interesting, but the practical decision remains its temperament: choose it for a planned aquarium, not as an automatic addition to a peaceful mixed collection.

Check the decisive care numbers before committing

Keep this fish at 20–22°C, pH 6.0–8.0 and 5–12 dGH. These routine values are the overlap of FishBase’s recorded environmental range, the Seriously Fish aquarium range and OATA’s gourami and Paradise Fish guidance. OATA’s figures apply to the wider group rather than representing a species-specific optimum.

Use an aquarium with a base of at least 80 × 30 cm, equivalent to approximately 72 litres. Seriously Fish presents that footprint and volume as the minimum considered for a single pair, while FishBase independently records a minimum aquarium length of 80 cm. Retain the 80 cm length when planning for one animal; do not treat the smaller dispatch fish as needing less permanent space.

Use the numbers together

A suitable temperature alone does not make an aquarium suitable. The footprint must accommodate territorial behaviour, the filter must process waste and potential companions must share the same environmental requirements. For example, an 80 cm aquarium at 21°C still fails the plan if ammonia or nitrite is detectable, while a larger mature aquarium still fails if its residents are timid, similarly shaped or small enough to be eaten.

Make the decision from the complete set: adult space, routine water values, established filtration and a compatible social plan. This prevents one favourable number from hiding a conflict elsewhere in the aquarium.

Understand the animal covered by one purchase

One purchase supplies one live Paradise Fish blue red. The dispatch grade associated with this offer is approximately 4–5 cm, while the permanent aquarium must be planned around the 8 cm adult length and the full territorial needs of the species. Dispatch length describes the fish at the point of supply; it is not an adult-size estimate or permission to begin with a smaller aquarium.

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

That distinction matters because male territorial behaviour affects social planning. Prepare an arrangement that remains safe if the animal proves to be male, rather than relying on colour, fin shape or its dispatch size to determine the aquarium plan.

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 image shows the elongated fins and alternating turquoise-blue and orange-red markings associated with the named strain. Treat the image as a guide to type and pattern rather than a promise of identical colour placement on every individual.

For other members of the same aquarium family, browse the gouramis and labyrinth fish collection. Compare each animal on its own adult size, water range and temperament rather than assuming that members of one family can share an aquarium.

Plan the aquarium around adult growth and floor space

Plan for an adult length of 8 cm standard length and an aquarium base of at least 80 × 30 cm. Seriously Fish gives approximately 72 litres as the equivalent volume and describes that footprint as the minimum considered for a single pair. FishBase also records a minimum aquarium length of 80 cm, so aquarium length remains a decisive requirement even when only one fish is planned.

Keep the size references in perspective

The 8 cm standard-length figure is the adult planning reference used throughout this care plan. FishBase records a different maximum of 6.7 cm standard length, while OATA describes Paradise Fish as growing to approximately 10 cm. These figures differ, so use 8 cm consistently for the permanent setup and leave a margin above the minimum footprint where the social arrangement adds pressure.

The 4–5 cm dispatch grade is not a separate space category. Place the fish directly into the mature aquarium intended for its adult needs. Moving a territorial fish through a succession of undersized aquariums creates avoidable setup changes and does not alter the species-level minimum footprint.

Choose shape before chasing litres

Volume and footprint answer related but different questions. The approximate 72-litre figure describes an aquarium based on 80 × 30 cm, while the base dimensions provide the horizontal room used in the minimum recommendation. A taller aquarium can hold the same number of litres without matching that footprint, so check the actual base dimensions rather than relying on the volume printed on the box.

• Suitable example: a mature aquarium measuring at least 80 × 30 cm at the base and holding around 72 litres or more.
• Unsuitable example: a tall aquarium that reaches 72 litres but has a base shorter than 80 cm.
• Social upgrade: choose more space when attempting a carefully assessed mixed or multi-fish arrangement.

Do not calculate capacity by dividing litres by fish length. Territorial behaviour, companion type, filtration and the physical layout all affect whether the aquarium works. Begin with the published footprint, then make the aquarium larger when the social plan becomes more complex.

Hold a cool, measured routine water range

Keep the aquarium at 20–22°C, pH 6.0–8.0 and 5–12 dGH. This set is the overlap of FishBase’s environmental figures, Seriously Fish aquarium guidance and OATA’s group range. Aim for measured values within all three bands rather than selecting the broadest upper or lower limit from just one reference.

Measure the aquarium you actually have

Test temperature and pH in the aquarium, and establish the general hardness of the water used for changes. The water chemistry guide explains the values to measure, while the water matcher helps compare those readings with the stated range. Record results so that gradual movement is visible rather than judging water from appearance alone.

Seriously Fish notes that this species can be maintained in an unheated aquarium in many cases and may benefit from a cool winter period. Treat “unheated” as a description of equipment, not a temperature target: it works only when repeated measurements remain inside the planned range. If the room allows the aquarium to fall below 20°C or rise above 22°C, manage the aquarium to restore the routine band.

Protect water quality as well as chemistry

Keep ammonia at 0 mg/l and nitrite at 0 mg/l. OATA also advises keeping nitrate no more than 20 mg/l above the normal level in the tap water used for the aquarium. These waste readings answer a different question from pH and hardness: water can have the right pH while still containing toxic ammonia or nitrite.

• If ammonia or nitrite is detected: stop treating the aquarium as ready for additional livestock and correct the water-quality problem.
• If pH or hardness sits outside the range: assess the source and replacement water before making further changes.
• If temperature moves through the day: compare readings at consistent times and address the condition causing the movement.

A larger aquarium generally offers greater environmental stability, but volume does not remove the need to test. Confirm the values at least weekly and whenever behaviour, breathing, colour or feeding changes.

Mature the filter before the fish enters the aquarium

Use a well-established biological filter and confirm that ammonia and nitrite are both 0 mg/l before introducing the fish. The RSPCA explains that biological filtration supports beneficial bacteria that convert toxic ammonia to nitrite and then to the safer nitrate. The labyrinth organ allows atmospheric breathing, but it does not process dissolved waste.

If this is your first setup, follow the first tropical aquarium guide and complete maturation before livestock arrives. Adding fish to an immature filter can create new tank syndrome because the bacterial population cannot yet process the increased waste.

Match the filter to the reference aquarium

Seriously Fish recommends turnover of four to five times the aquarium volume per hour for an aquarium of approximately 72 litres. That corresponds to a filter rated around 290–360 litres per hour. Use those figures to compare equipment for the reference setup, then account for the actual aquarium volume and the manufacturer’s rated performance.

Check the filter for blockages as part of routine maintenance. A filter cannot perform its biological role if flow is obstructed, but cleaning must preserve the bacterial population living in its media.

Follow a repeatable weekly routine

• At least once every week, carry out a partial water change of 25%.
• Use a siphon to remove solid waste from the gravel or sand where needed.
• Treat replacement tap water with conditioner to remove chlorine or chloramine before adding it.
• Test ammonia and nitrite at least once per week and keep both at 0 mg/l.
• Check nitrate against the normal level in the tap water and keep it within OATA’s stated limit.
• Inspect the filter for blockage and confirm that water is moving through it.

If filter media needs cleaning, do not run it under the tap. Rinse it lightly in aquarium water removed during the partial water change. This reduces the loss of beneficial bacteria and keeps filter maintenance tied to the established weekly routine.

Furnish the aquarium with cover and clear sight checks

Use a fully decorated aquarium with gravel or sand, live plants and structured cover. Seriously Fish recommends driftwood roots and branches arranged to create shady areas, while OATA advises aquarium substrate and ideally live plants. These features break up an otherwise open layout and provide places where a fish can move out of direct view.

Build structure without losing access

Place wood and plants so that the aquarium contains sheltered areas as well as open routes for swimming. Keep enough access to siphon waste and inspect the fish from both sides. A decorative layout only helps when maintenance can still reach the substrate and the keeper can see changes in fins, scales, body condition and behaviour.

• At the base: use aquarium gravel or sand that can be cleaned during water changes.
• Through the middle: arrange roots, branches and plants to create shade and visual separation.
• At the surface: floating or surface vegetation can be included when breeding is the aim.
• Around equipment: leave the filter accessible for blockage checks and careful cleaning.

Dried leaf litter can reinforce a natural appearance and support colonies of microbes that may provide early food for fry. That benefit belongs to a breeding context rather than the everyday feeding plan for an adult fish, so do not rely on leaf litter as the animal’s main food source.

Respect its air-breathing biology

Paradise Fish possess a labyrinth organ and breathe atmospheric air. Expect the fish to use the surface as part of normal biology, but assess surface visits alongside its usual pattern. OATA advises watching for changes such as hanging at the surface, erratic swimming or altered breathing rate because a change from the individual’s normal behaviour can point to a developing health or water-quality problem.

Do not use atmospheric breathing as a reason to reduce filtration, water changes or testing. The aquarium still needs a functioning biological filter, 0 mg/l ammonia, 0 mg/l nitrite and a regular maintenance routine.

Feed an animal-based diet in controlled portions

Make small live or frozen animal foods the core of the feeding plan. Seriously Fish recommends Daphnia, Artemia, white worm and grindal worm, reflecting a wild diet likely to include insect larvae. FishBase also records feeding on small aquatic animals, including small fish. These species-level diet notes make animal-based foods the appropriate staple direction.

Some high-quality dried products may also be accepted, particularly by ornamental strains. Treat acceptance as something to observe rather than assume. A food that remains untouched is not contributing variety and can break down into waste.

Use a simple daily portion rule

Feed once a day and offer only what the fish can eat within a few minutes. OATA applies this portion and frequency guidance to gouramis and Paradise Fish. Remove or reduce any food that repeatedly remains after that window because overfeeding can create uneaten waste and increase the burden on the filter.

• Main rotation: suitably small live or frozen Daphnia, Artemia, white worm or grindal worm.
• Additional variety: small bloodworm or tubifex, as included in OATA’s group feeding guidance.
• Secondary dried food: a high-quality product when the individual accepts it.
• Portion: only the amount eaten within a few minutes, once a day.

Let feeding behaviour guide the next check

Watch the whole feed rather than dropping food and walking away. Confirm that the fish approaches food, takes it normally and maintains body condition. A reduced intake or lack of interest is one of OATA’s warning signs, especially when it appears alongside altered swimming, colour, breathing or temperament.

If food remains, reduce the next portion and remove accessible waste during maintenance. If appetite changes suddenly, test ammonia and nitrite rather than trying several new foods at once. Keeping the diet varied but the portion rule consistent makes it easier to distinguish preference from a broader health or water-quality change.

Prepare the mature aquarium before arrival

Complete the aquarium, establish the filter and confirm 0 mg/l ammonia and 0 mg/l nitrite before the fish arrives. Check that temperature, pH and hardness are already within the planned range. Add livestock gradually because every new fish and increase in feeding requires the filter’s bacterial population to process more waste.

Tropical Fish Co animals are hand-bagged in pure oxygen, placed in an insulated poly box and accompanied by a heat pack when the weather calls for it. Follow the current delivery and Live Arrival Guarantee policy for the full terms.

Follow these arrival steps in order

1. Be at the delivery address to receive the parcel; live fish cannot be left unattended.
2. Start filming before opening, with the parcel still sealed and the outer box visible.
3. Open the parcel in one continuous take and show the fish inside the sealed bag before anything is disturbed.
4. Open and inspect the parcel on the same day it arrives.
5. Float the bag for 20–30 minutes before releasing the fish.
6. Do not pour the bag water into the aquarium.
7. If anything has gone wrong, report it the same day with the order number and continuous unboxing video.

Protect the established filter after introduction

Resume the normal testing routine after release and watch the fish during its daily feed. OATA advises increasing aquarium population slowly because stocking too quickly can produce unhealthy ammonia and nitrite levels. Do not add another animal merely because the first readings appear normal immediately after introduction; continue checking how the biological filter responds.

Keep the social plan conservative while the individual’s behaviour becomes clear. This offer does not guarantee sex, and male territorial aggression can intensify during reproductive periods. Beginning with a plan for one fish avoids committing the aquarium to a group arrangement before sex, space and compatibility have been assessed.

Respond early to changes in behaviour or condition

Observe the fish during its once-daily feed and compare what you see with its normal pattern. OATA recommends watching swimming, colour, temperament, breathing, physical appearance, body condition and food intake. A single observation becomes more useful when it can be compared with the fish’s usual behaviour and the latest water test.

Use each sign to trigger a practical check

• Hanging at the surface, sitting on the bottom or erratic swimming: test water quality and check filter operation.
• Darker or paler colour: look for accompanying changes in behaviour, breathing or social pressure.
• More aggression or hiding than normal: reassess the layout and every companion against the compatibility rules.
• Faster or slower gill-cover movement: test ammonia and nitrite and inspect the fish for other visible changes.
• White spots, fluffy growths, damaged fins, missing scales, ulcers or bumps: record what is visible and isolate the water-quality facts before choosing any response.
• Weight change or reduced feeding: review the daily portion, uneaten waste and recent test results.

Check the environment before guessing at a cause

Test ammonia and nitrite first and confirm both remain at 0 mg/l. Then check temperature, pH and the filter for blockage. This sequence identifies immediate husbandry problems that can affect any fish and gives a clear set of readings to accompany the observed sign.

Do not begin a disease treatment from appearance alone. Different problems can produce similar behaviour, and a treatment choice is not part of routine Paradise Fish care. If the change persists or the fish’s condition concerns you, contact us with the water readings and a concise description of what changed.

Plan for one fish unless the group is deliberately assessed

Begin with a solitary plan. OATA describes Paradise Fish as semi-aggressive and usually best kept on their own, while FishBase records that males fight. Seriously Fish adds that males are territorially aggressive, with the behaviour becoming more pronounced during reproductive periods.

Avoid casual male combinations

Seriously Fish says males should not be housed together unless the aquarium is very large. Plan one potentially male Paradise Fish per setup unless you have a very large aquarium and the complete arrangement has been assessed.

When a deliberately sexed arrangement contains one male and females, provide two or more females per male to disperse male attention. The offer here does not guarantee sex, so do not order several animals and assume their eventual composition will match that ratio.

• One fish: the clearest starting arrangement for the stated offer.
• Two males: avoid unless the aquarium is very large and the complete arrangement has been assessed.
• One male with females: Seriously Fish advises two or more females per male.
• Unsexed group: do not rely on colour, fin length or dispatch size to produce a safe ratio.

Allow for reproductive territoriality without planning a spawn

The species is a bubble nester, and male territorial behaviour can increase during reproductive periods. That biological fact matters even when breeding is not the goal because a social arrangement that appears calm can change. Include structured cover and enough room to separate lines of sight, but do not treat decoration as a substitute for the male-housing rule.

If territorial pursuit prevents another fish from feeding, keeps it hidden or causes fin and scale damage, the social arrangement is not working. Reassess the occupants rather than waiting for the minimum aquarium dimensions to solve a behavioural conflict.

Screen every possible companion against the avoid list

Consider only robust tankmates and peaceful schooling fish with comparable environmental requirements. Those descriptions are screening categories, not a universal tank-mate list. Every candidate must also fit 20–22°C, pH 6.0–8.0, 5–12 dGH and the available aquarium space.

Avoid the combinations named in the care guidance

• Similarly shaped fish: Seriously Fish says these should be avoided.
• Timid species: OATA says to avoid them with semi-aggressive Paradise Fish.
• Small fish that could be eaten: avoid them; the wild diet includes small aquatic animals and small fish.
• Fish that may nip its fins: avoid them because this strain has extended, exposed fins.
• Another male Paradise Fish: avoid this combination unless the aquarium is very large.

Do not move an animal from the avoid list into the plan merely because the aquarium is mature or the water values match. Water compatibility cannot cancel predation risk, timid behaviour, fin-nipping or a similarly shaped profile.

Use a complete screening sequence

1. Confirm that the candidate can live within 20–22°C, pH 6.0–8.0 and 5–12 dGH.
2. Reject it if it is timid, similarly shaped, small enough to be eaten or likely to nip fins.
3. Confirm that the aquarium exceeds the minimum where the extra occupant increases territorial or filtration pressure.
4. Check that ammonia and nitrite are 0 mg/l before adding anything.
5. Add fish gradually and watch feeding access, hiding and aggression after introduction.

Treat fish and invertebrates outside the named categories as case-by-case decisions. Provide the exact species, aquarium dimensions, water readings and present occupants when you ask us for a compatibility assessment. Shared temperature alone is not enough to approve a companion.

If the Paradise Fish begins pursuing a companion, blocks it from food or drives it into continuous hiding, act on the observed conflict. Recheck the avoid criteria and change the social arrangement rather than assuming the behaviour will disappear.

Answer the questions keepers ask before buying

How big does the Paradise Fish blue red get?

The Paradise Fish blue red reaches 8 cm standard length according to Seriously Fish. Plan the permanent aquarium around that adult figure rather than the approximately 4–5 cm dispatch grade.

What size aquarium does Macropodus opercularis need?

Use an aquarium with a base of at least 80 × 30 cm, equivalent to approximately 72 litres. Seriously Fish gives this as the minimum for a single pair, and FishBase also records a minimum aquarium length of 80 cm.

How many Paradise Fish blue red should I keep together?

Plan to keep one Paradise Fish blue red unless the group is deliberately assessed. Seriously Fish advises two or more females per male and says males should not be housed together unless the aquarium is very large.

Does it suit a beginner?

It can suit a prepared beginner who can measure the cool routine water range, maintain a mature filter and manage semi-aggressive territorial behaviour, but it is not an automatic choice for a peaceful mixed community.

What does the Paradise Fish blue red eat?

Feed the Paradise Fish blue red small live or frozen Daphnia, Artemia, white worm or grindal worm as its main rotation. Offer only what it eats within a few minutes once a day; some high-quality dried foods may also be accepted.

What temperature and pH does this fish need?

Keep it at 20–22°C, pH 6.0–8.0 and 5–12 dGH, the overlap of FishBase, Seriously Fish and OATA group guidance. Maintain ammonia and nitrite at 0 mg/l.

Does it become aggressive or nip fins?

It can be semi-aggressive, and males are territorially aggressive, especially during reproductive periods. Avoid another male unless the aquarium is very large, and avoid companions that may nip the Paradise Fish’s fins.

Which animals can live with a Paradise Fish blue red?

Consider robust tankmates or peaceful schooling fish with comparable environmental requirements. Avoid timid species, similarly shaped fish, small fish that could be eaten and fish that may nip its fins.

How does this fish arrive alive in the UK?

Start filming with the parcel still sealed before opening or floating the bag. Tropical Fish Co hand-bags the fish in pure oxygen, uses an insulated poly box and adds a heat pack when the weather calls for it; be present to receive it, inspect it the same day and float the bag for 20–30 minutes before release.

Read the care and identity references

• FishBase: Macropodus opercularis — identity, family, distribution, wild habitat, environmental records, diet, behaviour and recorded length.
• Seriously Fish: Macropodus opercularis — aquarium dimensions, water conditions, adult length, diet, furnishing and social behaviour.
• OATA: How to look after gouramis and Paradise Fish — group water, feeding, maintenance, introduction and compatibility guidance.
• RSPCA aquarium environment advice — biological filtration and aquarium waste processing.