By Tom Whitfield
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.
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.
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.
| Form | Look | Care | Notes |
|---|---|---|---|
| Classic (wild) blue-red | Alternating blue-green and red vertical bars | Easy | The historic, most recognisable form |
| Red / red velvet | Predominantly deep red | Easy | Colour intensifies on conditioning |
| Blue | Strong blue dominance | Easy | Same care as classic |
| Albino | Pale body, red eyes, soft colour | Easy | A touch more light-sensitive |
| Chinese paradise (M. chinensis) | Plainer, round-tailed | Very easy | Separate 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.
