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Gouramis & Labyrinth Fish · Buying Guide

Paradise Fish UK: Macropodus opercularis Care, Colour Forms & Live Stock

Paradise fish (Macropodus opercularis): one of the oldest aquarium fish, stunning, hardy and happy in an UNHEATED tank (16-26C) - but feisty. Honest care + live UK stock.

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Tom WhitfieldBy Tom WhitfieldUpdated 21 June 202610 min read
A male paradise fish (Macropodus opercularis) showing electric blue and red vertical barring with flowing fins in a planted aquarium
Editorial illustration - Tropical Fish Co· Own
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Ideal water conditions at a glance

The shaded band shows the range paradise fish is comfortable in. Match it to your tap water before you buy.

Temperature16–26 °C
18 °C32 °C
pH6–8
59
Hardness5–20 dGH
0 dGH30 dGH

The fish that started the hobby - and still earns its place

The paradise fish, Macropodus opercularis, is widely cited as one of the first tropical fish ever kept in Western aquariums - a fish people were keeping over 150 years ago, long before neon tetras or guppies. Look at a male in full colour, with electric-blue and red vertical bars and trailing fins, and it's obvious why it caught on. What's less obvious from a shop tank is that this is one of the hardiest and most cold-tolerant colourful fish in the trade - and one of the feistiest for its size.

I'm Tom Whitfield, and labyrinth fish are my corner of Tropical Fish Co. The paradise fish is a species I recommend often, but always with the same two-line briefing: it's gorgeous and bombproof, and it has a temper. This page is that briefing in full - what they need, why they don't need a heater, who they can (and can't) live with, and which colour forms we have in stock.

Why paradise fish are different: cold-hardy and air-breathing

Two facts shape everything about keeping this fish.

  • They tolerate cool water. FishBase lists a temperature range of 16-26 C for Macropodus opercularis [1]. In practice that means a paradise fish is comfortable at normal UK room temperature - this is a colourful "tropical" fish you can keep in an unheated tank, which is unusual and genuinely useful.
  • They breathe air. As a labyrinth fish (family Osphronemidae), the paradise fish has an accessory breathing organ and is an obligate air-breather, able to colonise the warm, stagnant, low-oxygen ditches and paddy fields it comes from across China, Taiwan and northern Vietnam [1]. In the tank, that means regular trips to the surface to gulp air - so a tight lid (they jump) and a warm, humid air gap above the water are essential.
A great fish for an unheated tank

If you want colour in a cold spare room, an office, or a low-tech setup without a heater, the paradise fish is one of the best choices in the hobby. Keep a low-wattage heater on a ~18 C backstop for winter cold snaps if you like, but day-to-day warmth isn't required.

The honest part: temperament and tank mates

This is the section that should decide your stocking plan. Paradise fish are territorial, and males particularly so. Two males will fight, and a male will harass other long-finned or similar-shaped fish - bettas, gouramis and fancy guppies are all read as rivals and risk fin damage [3]. They're also carnivorous micropredators that eat small aquatic animals in the wild [1], so shrimp, fry and very small fish tend to vanish.

The practical rules:

  • One male per tank. Always.
  • Best kept as a single specimen or a male-female pair in a planted species tank.
  • If you want tank mates, choose fast, robust, short-finned fish in a roomy, heavily-planted tank (some barbs, larger tetras, Corydoras) - and watch for trouble.
  • Never house a paradise fish with a betta, or with other labyrinth fish.
Not a peaceful community fish

The most common paradise-fish mistake is dropping one into a mixed community of guppies, gouramis or a betta. It looks peaceful for a week, then fins start to shred. Plan the tank around the paradise fish's temperament from the start - a species tank is never the wrong answer with this fish.

Colour forms - all one species (plus one relative)

The red, blue, blue-red, albino and "fire/velvet" paradise fish you'll see are all selectively-bred or wild colour forms of the same species, Macropodus opercularis, with identical care [1]. One label worth knowing: the Chinese / round-tail paradise fish, Macropodus chinensis, is a separate but closely-related species [2] - plainer in colour, with a rounder tail, and even more cold-tolerant. We list the exact species on every product so you know what you're getting.

FormLookCareNotes
Classic (wild) blue-redAlternating blue-green and red vertical barsEasyThe historic, most recognisable form
Red / red velvetPredominantly deep redEasyColour intensifies on conditioning
BlueStrong blue dominanceEasySame care as classic
AlbinoPale body, red eyes, soft colourEasyA touch more light-sensitive
Chinese paradise (M. chinensis)Plainer, round-tailedVery easySeparate species; extremely cold-hardy

Tank setup checklist

  • Tank: 60 L+ planted, longer rather than taller, with a calm surface.
  • Lid: tight-fitting and complete - paradise fish jump, and they need a warm humid air layer for the labyrinth organ.
  • Filtration & flow: gentle. They dislike strong current; a sponge or baffled filter is ideal.
  • Planting & cover: dense planting and floating plants to break sightlines and reduce aggression; this matters more with paradise fish than with most species.
  • Water: undemanding - pH 6.0-8.0 and hardness 5-19 dH, so standard hard UK tap water is fine [1].
  • Temperature: 16-26 C; no heater required in a normal room.

Here are the paradise fish we have in stock - the species and colour form is named on each listing:

Is a paradise fish right for you?

Choose a paradise fish if you want a strikingly colourful, historic, genuinely hardy fish that doesn't need a heater and you're willing to build the tank around its temperament - one male, a species tank or carefully-chosen robust companions, and plenty of cover. Avoid it if you wanted a peaceful centrepiece for a mixed community of guppies, gouramis or a betta. Get the stocking right and it's one of the most rewarding low-fuss fish in the hobby - a living piece of aquarium history.

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Frequently asked questions

No - and that's a big part of their appeal. FishBase lists a temperature range of 16-26 C for Macropodus opercularis, so a paradise fish is comfortable at typical UK room temperature and is one of the few colourful 'tropical' fish you can keep in an unheated tank [1]. A heater set to a low backstop (around 18-20 C) is still sensible for a cold spare room or a winter cold snap, but day to day they don't need tropical warmth. This cold-tolerance is why they're an excellent choice for a low-tech or first aquarium.
Paradise fish are territorial, especially the males, and they are not a safe bet for a typical peaceful community. Two males will fight, sometimes seriously, and a male will harass other long-finned or similar-shaped fish - bettas, gouramis, fancy guppies - as rivals [3]. The honest rule is: keep ONE male per tank. They can work with fast, robust, short-finned companions (some barbs, larger tetras, Corydoras) in a roomy, well-planted tank, but many keepers get the best results keeping them as a single specimen or a male-female pair in a species tank. Never house a paradise fish with a betta.
A single male or a male-female pair is comfortable in a 60 litre (around 2 ft) planted tank; give them more if you want to keep a small group or add tank mates. Footprint and cover matter more than sheer volume: they're surface-oriented labyrinth fish, so a longer tank with a calm surface, plenty of planting to break sightlines, and floating cover suits them better than a tall narrow one.
Small - around 6 to 7 cm. FishBase records a maximum standard length of 6.7 cm, with a common length closer to 5.5 cm [1]. Males grow slightly larger than females and develop longer, more flowing fins and more intense colour, particularly when displaying or defending territory.
That's completely normal. Paradise fish are labyrinth fish: they have an accessory breathing organ that lets them take oxygen directly from the air, which is how they survive the warm, low-oxygen ditches, paddy fields and backwaters they come from [1]. In the aquarium they'll regularly rise to gulp air at the surface. Two practical points follow: keep a tight-fitting lid (they can jump), and leave a warm, humid air gap between the water and the lid - a cold draught on the surface can chill the labyrinth organ.
They're carnivorous micropredators - in the wild they eat small aquatic animals, including small fish and invertebrates [1]. In the aquarium they're easy: a good-quality flake or micro-pellet as a staple, with frozen and live foods (bloodworm, daphnia, brine shrimp) several times a week for colour and condition. Their appetite for small live prey is exactly why tiny tank mates - shrimp, fry, very small fish - tend to disappear.
No to bettas, and be cautious with gouramis. Paradise fish are close relatives of bettas and gouramis (all labyrinth fish), and that's the problem - males read similar-shaped, long-finned fish as rivals and will fight or fin-nip them [3]. A betta and a paradise fish in the same tank is a recipe for injury. If you want a labyrinth fish display, pick ONE species per tank.
The red, blue, blue-red, albino and 'fire/velvet' forms of Macropodus opercularis are all the same species - selectively bred or wild colour variants, with identical care [1]. One thing to know: the Chinese or round-tail paradise fish (Macropodus chinensis) is a separate, closely related species [2] - it's plainer but even hardier and more cold-tolerant. Check the label if the exact form matters to you; we list the species on each product.
They're bubble-nest breeders, like bettas. A conditioned male builds a raft of bubbles at the surface (often under a floating leaf), then entices the female beneath it; the eggs are placed in the nest and the male guards and tends them until the fry are free-swimming. Breeding is achievable for a hobbyist in a quiet, well-planted tank, but the male can be rough on the female during and after spawning, so provide dense cover and be ready to separate them.
Buy on condition, not impulse. Look for a fish that's alert and showing colour (a stressed paradise fish goes pale and barred), with clean, unsplit fins, clear eyes and no clamped or laboured breathing. A single confident male is usually a better buy than one cowering in a crowded tank. Online is fine when the seller packs in an insulated, oxygenated bag and uses a licensed live-animal courier - and because paradise fish are cold-hardy, they travel and acclimatise more forgivingly than many tropicals.

Sources & further reading

Material factual claims cite the sources below; store policy and cautious inference are labelled in the article. Sources are grouped by type so you can judge their weight at a glance.

Peer-reviewed study (1)

  1. [2]
    Freyhof, J. and F. Herder (2002). Review of the paradise fishes of the genus Macropodus in Vietnam, with description of two species from Vietnam and southern China. Ichthyological Exploration of Freshwaters 13(2):147-167. View source

    Taxonomic revision of the genus Macropodus - basis for distinguishing M. opercularis from related species such as M. chinensis.

Scientific database (2)

  1. [1]
    Froese, R. and D. Pauly (Eds.) (2024). Macropodus opercularis (Linnaeus, 1758) - Paradisefish. FishBase. View source

    Source for maximum size (6.7 cm SL), temperature range (16-26 C), pH (6.0-8.0), hardness (5-19 dH), obligate air-breathing, diet and East Asian distribution.

  2. [5]
    (2024). Macropodus opercularis (Linnaeus, 1758) - taxonomic record. ITIS (Integrated Taxonomic Information System). View source

    Accepted scientific name, authority (Linnaeus, 1758) and classification within Osphronemidae.

Conservation authority (1)

  1. [4]
    (2024). Macropodus opercularis - IUCN Red List assessment. IUCN Red List of Threatened Species. View source

    Conservation status and natural range of the species (assessed Least Concern; wide East Asian distribution).

Hobbyist reference (1)

  1. [3]
    (2024). Macropodus opercularis (Paradise Fish). Seriously Fish. View source

    Aquarium husbandry, aquascaping and temperament guidance for a territorial labyrinth fish.

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