André Karwath aka Aka, edited by Muhammad · CC BY-SA 2.5 — Wikimedia Commons

Freshwater Fish · Gouramis

Paradise Fish

Macropodus opercularis

The hobby's first tropical fish, with a temperIntermediate

Lifespan: 6-8 years, occasionally 10
Size: 3-4in / 8-10cm including tail streamers
Social needs: One male alone, or one male with 2-3 females in 30gal+; never two males
Time: 10-15 min daily; weekly water change
Cost: Low
Diet: Omnivore, insect-leaning (pellets, frozen bloodworm, brine shrimp)

Overview

What is this animal?

The paradise fish was the first tropical aquarium fish kept in the West, arriving in Paris in 1869 and captivating keepers decades before the betta.
Males wear alternating blue and red-orange vertical bars and trail a deeply forked tail into long streamers, so a good specimen still looks remarkable today.

What separates it from the dwarf, honey, and pearl gouramis elsewhere on this site is that it is subtropical, not tropical, and lives happily in an unheated indoor tank between about 61 and 79F (16-26C).
It pairs that toughness with the sharpest temper of any gourami here, behaving more like a territorial wild betta than like its placid cousins.

The hardiness is real, but so is the aggression, and the species suits a keeper willing to plan the whole tank around one fish.
It rates Intermediate not because it is hard to keep alive, but because it is hard to keep with anything else.

Temperament

Expect a bold, intelligent fish that watches the room, learns the feeding routine, and begs at the glass with real personality, much like a betta but with more presence.
Kept alone, it makes an outstanding single wet pet in the way a betta does.

Toward other fish it is the least forgiving gourami in the hobby.
Males flare and fight each other seriously, and slow, long-finned, or small tankmates such as bettas, fancy guppies, dwarf gouramis, and shrimp will be harassed, shredded, or eaten.

In larger tanks, fast, robust, similar-sized schoolers such as giant danios or larger barbs can hold their own, but every community attempt needs an exit plan.
Males build bubble nests and drive females hard during spawning, so a spawned female needs cover and usually removal afterward.

A good fit for

Keepers wanting a striking fish for an unheated tank
A single wet pet with betta-like personality and more presence
Experienced keepers who can stock around one boss fish
Fans of aquarium history keeping the original tropical fish
Low-tech planted setups without a heater

Common mistakes to avoid

Two males will fight to serious injury — never together
Shreds or eats slow, long-finned, and small tankmates
Hardy reputation misused to justify bowls and dirty water
Jumps — a tight-fitting lid is essential
Often mis-sold as a peaceful community gourami
Shrimp and fry are prey, not tankmates

Enclosure

Minimum 75 litres (20 US gallons)

Must be housed alone. One male alone, or one male with 2-3 females in 30gal+; never two males

A single paradise fish needs a 20 gallon long (75L) at minimum, and the long, shallow footprint matters because this is a patrolling surface-oriented fish, not a tall-tank fish.
Furnish densely with plants, floating cover, and broken sight lines, keep flow gentle, and leave a calm surface, because like all gouramis it is a labyrinth breather that must sip air.
A tight-fitting lid is non-negotiable, both because it is an accomplished jumper and because it needs a layer of warm, humid air above the water.

Room temperature is genuinely fine, which makes this one of very few striking fish for heaterless setups, though it should not sit below about 55F (13C) for long and sustained temperatures above 80F (27C) run its metabolism hot.
Water chemistry is exceptionally forgiving, with soft to hard water and a pH anywhere from about 6.0 to 8.0 accepted.

Never house two males together, because they will fight until one is seriously injured or dead.
One male with two or three females can work in a heavily planted 30 gallon (110L) or larger, and females alone can be kept in small groups though they will still squabble, but the classic arrangement is a single male as the tank's only paradise fish.

Check your enclosure

Supplies

Setup

Tank and stand
Filter
Heater and thermometer
Substrate, plants and decor
Liquid test kit
Dechlorinator and starter supplies

Ongoing

Quality tropical flake
Floating and slow-sinking micro-pellets
Frozen bloodworm, brine shrimp and daphnia
Spirulina or vegetable flake
Courgette for blanching
Veg clip
Fine net for removing leftovers

Safe substrate: Inert aquarium gravel · Fine, smooth sand · Aquasoil for planted tanks

Work out the cost

Care routine

Daily

Check temperature and equipment
Feed
Head-count and look everyone over

Weekly

Check the air layer above the waterevery 3 days
Top up evaporationevery 3 days
Clean glass and clear algae
Test the water
Water change and gravel vacuum

Monthly

Trim and thin the plantsevery 2 weeks
Check supplies and reagent dates
Rinse the filter media

Less often

Replace chemical filter media (Carbon/Purigen)every 2 months

Vet: Quarterly review with a surface-air check — every 3 months

Top resources for more info

Independent creators and organisations we would send a friend to. We have no affiliation with any of them, and nothing here is sponsored. Links checked 2026-09-19.

YouTubers

Girl Talks FishCare how-tos by fish type, tank setup and beginner mistakes Aquarium Co-OpSpecies care guides, filtration and fish health (run by a retailer)Prime Time AquaticsSpecies profiles, stocking and water chemistry explained plainly

Sites

Seriously FishSpecies profiles with tank size, water parameters and diet for 1,800+ fish Practical FishkeepingLong-running UK fishkeeping magazine with care and species articles FishLoreCare profiles and a large keeper forum for freshwater and saltwater fish

Go deeper

Diet

Paradise fish are omnivores that lean strongly toward insects and other live prey.
Feed a quality insect-based pellet or flake as the staple, rotated with frozen or live bloodworm, brine shrimp, daphnia, and mosquito larvae to keep colour and condition up.

Anything that fits in its mouth is food, so cherry shrimp, fry, and the smallest nano fish are prey items, not tankmates.
It will also pick snails and small pest invertebrates off the glass, which some keepers count as a feature.

Feed once or twice daily, offering only what is finished within two minutes.
This is a greedy, gorging feeder that becomes obese on generous portions, so lean feeding with an occasional fast day serves it better.

Health

This is one of the hardiest aquarium fish ever kept, and that reputation is the biggest threat to its welfare, because it is still used to excuse bowls, unfiltered tanks, and neglected water.
A paradise fish surviving bad conditions is not thriving in them, and proper filtration plus a weekly water change is what turns survival into a 6-8 year lifespan.

Most real injuries are social rather than infectious, with torn fins and scale damage from fights or harassment opening the door to fungus and bacterial infection.
Check fins weekly, and treat any ragged edges as a stocking problem to fix, not just a wound to medicate.

Beyond that, watch for ich after temperature swings in unheated rooms, and keep the surface air warm and humid under the lid to protect the labyrinth organ.
Quarantine new arrivals as standard.

Is your enclosure big enough?

Minimum volume75 litres (20 US gallons)

CompanyMust be housed alone. One male alone, or one male with 2-3 females in 30gal+; never two males

Length

Width

Height

Units

Or tank volume

Units

Is this urgent?

In a fish tank the patient is usually the water. Test before you treat — dosing a healthy tank for a disease it does not have makes things worse.

Go now

Any detectable ammonia or nitrite in a stocked tankLarge water change now with dechlorinated, temperature-matched water. Stop feeding. Test again in 12 hours. Both are directly toxic. How toxic the ammonia reading is depends on pH and temperature, so the same number can be harmless or lethal.

Now

Fish gasping at the surface, or crowding the filter outflowIncrease surface agitation immediately, then test the water. Either the oxygen has crashed or the gills are being chemically burned. Both are hours-scale problems.

Now

Sudden deaths, more than one fish in a dayTest ammonia, nitrite, nitrate and temperature before doing anything else. Do not add medication yet. Multiple simultaneous deaths point at the water or the equipment, not at a pathogen.

Now

Today

Flashing — repeatedly scraping against decor or substrateTest the water, then look closely for parasites. Irritation is either chemical or parasitic; the test tells you which before you medicate.

Today

White salt-grain spots over the body and finsBegin the appropriate treatment today and check the temperature. The parasite's life cycle is temperature-driven, and it multiplies with every cycle you wait.

Today

Soon

Clamped fins, hiding, or refusing food for more than two daysTest the water and review recent changes. Usually the earliest visible sign of a parameter drifting.

A few days

Never add a new fish to a tank that is not fully cycled, and never treat blind. A test kit is cheaper than the fish.

This is general guidance for a healthy adult, not a diagnosis. An exotics vet who knows your animal always overrides it — and the time to find one is before you need one.

What it really costs

Setup, monthly, first year and across a whole life, itemised and with the electricity worked out from the actual wattage. Published figures for the same animal disagree by a factor of four, so the calculator shows ranges rather than picking one.

Region

How many animals

Your electricity price, per kWh

Buying the setup

Bedding and substrate

Substrate in an aquarium is a filter as much as a floor. Most of the biology lives in and on it.

Safe

Inert aquarium gravelRinse thoroughly before use. Grain size should be too large to swallow and too small to trap food.

safe

Fine, smooth sandCorrect for corydoras, kuhli loaches and anything that sifts. Their barbels wear away on sharp gravel.

safe

Aquasoil for planted tanksExcellent for plants, but it leaches ammonia for the first weeks. Cycle around it; do not stock into it.

safe

Bare bottomLegitimate for quarantine and grow-out tanks. Easy to clean, but it holds far less biological filtration.

safe

With a caveat

Crushed coral or aragoniteDeliberately raises hardness and pH. Correct for rift-lake cichlids, wrong for soft-water species.

with a caveat

Very deep sand bedsAnaerobic pockets form below about 5 cm in still sand. Either keep it shallow or keep it stirred.

with a caveat

Painted or coated gravelUsually fine, but coatings chip. Test a handful in a jar for a week first.

with a caveat

Never

Sharp or angular gravel with bottom-dwellersWears down barbels and leads to infection in corydoras and loaches.

never

Anything containing metal, limestone of unknown origin, or shells in a soft-water tankSlowly alters chemistry in ways that are hard to diagnose later.

never

This is our general list for freshwater fish. We have not built one specific to Gouramis yet.

My kit says 0.25 ppm. Is that dangerous?

A liquid kit measures total ammonia, but only the un-ionised fraction is really toxic, and that fraction is governed by pH and temperature — each whole pH unit multiplies it roughly tenfold. So the same reading can be nearly harmless in one tank and lethal in another; this works out which one you are in.

Total ammonia, ppm

Temperature, C