The Complete Gouramis & Bettas Guide: Labyrinth Fish Care

Betta splendens, the Siamese fighting fish, is only the most familiar member of Anabantoidei, a suborder of labyrinth fishes that also includes the honey gourami, pearl gourami, paradise fish, chocolate gourami, licorice gouramis, climbing perch, and several large food fishes. The group is united less by colour than by physiology: a specialised air-breathing organ in a chamber above the gills allows these fishes to exploit warm, stagnant, tannin-stained waters where ordinary gill breathers would struggle.

I have kept Southeast Asian blackwater tanks for more than thirty years, including peat-swamp setups for Parosphromenus and quiet planted aquaria for Trichopsis. Anabantoids reward careful keepers because their behaviour is visible at close range: males court, flare, croak, build bubble nests, guard fry, or brood eggs in the mouth. Distinguishing gourami flaring display from aggression is a practical skill when running mixed pairs or trios. They also punish lazy assumptions. A betta in an uncycled vase is not a hardy fish; it is a fish being forced to survive by breathing air while ammonia damages the gills.

Taxonomy

Anabantoidei sits within the order Anabantiformes. The aquarium trade uses "labyrinth fish" broadly for several related families: Osphronemidae contains bettas, gouramis, and giant gouramis; Anabantidae contains climbing perches; Helostomatidae contains the kissing gourami. Modern genus names have shifted. The dwarf gourami and honey gourami are now usually placed in Trichogaster, while the pearl and three-spot gouramis are Trichopodus. Older books may reverse those names, so reading the date of a source matters.

The family-level split is useful for husbandry. Betta, Trichopsis, Parosphromenus, and Sphaerichthys include small blackwater fishes that are sensitive to hardness and bacterial load. Trichopodus contains medium gouramis that fit larger planted community tanks. Osphronemus and Helostoma are large-bodied fishes that outgrow ordinary home aquaria. Anabas is hardy, predatory, and physically strong enough to leave an uncovered tank.

Identification

The diagnostic feature is the labyrinth organ, a folded vascularised structure inside a suprabranchial cavity. It develops as juveniles mature and is not the same evolutionary solution as the intestinal or swim-bladder air-breathing seen in some catfishes and cyprinids. Labyrinth fishes still use their gills; atmospheric breathing supplements gill respiration and becomes compulsory in many species. A healthy betta or gourami rising to sip air is not gasping in the emergency sense. A fish parked at the surface, breathing rapidly through the opercula, is a different case and usually indicates ammonia, nitrite, heat stress, or gill disease. Bottom-laying in bettas is the resting-on-substrate variant of the same emergency pattern.

Most anabantoids have a laterally compressed body, small upturned mouth, and long pelvic filaments in the gouramis. Bettas have shorter bodies and more obvious male finnage. Trichopsis species can produce audible croaks by specialised pectoral mechanisms. Kissing gouramis are distinctive because the thickened lips scrape algae and are also used in ritualised mouth pushing. Climbing perch have a deeper body, spiny gill covers, and a reputation for short overland movement during wet conditions.

Behaviour & Ecology

The ecological centre of the group is Southeast Asia: peat swamps, rice paddies, vegetated ditches, oxbows, blackwater forest streams, and floodplain pools. These waters are often warm, shallow, low in dissolved oxygen, and rich in leaf-derived humic substances. The labyrinth organ turns atmospheric oxygen into a usable resource, letting anabantoids forage where many competitors are excluded.

Bubble-nest spawning is the behaviour most aquarists recognise. A male traps air bubbles at the surface, coats them with mucus, courts the female under the nest, and wraps around her in a tight embrace. Eggs and sperm are released during the clasp. In Betta splendens, Trichogaster, Trichopodus, and Macropodus, the male gathers falling eggs and tends the nest until the fry become free-swimming. The keeper's task is to protect the warm humid air layer above the nest and remove adults at the right moment for that species.

Mouth-brooding evolved in several lineages. Wild Betta macrostoma males carry eggs in the mouth and may swallow a brood if stressed. Chocolate gourami females brood eggs orally. These fishes cannot be treated like nest-builders; disturbance, netting, or aggressive tankmates can end a spawn in minutes.

Water Chemistry & Habitat

There is no single anabantoid water recipe. A licorice gourami from a peat swamp and a paradise fish from cooler East Asian ditches are both labyrinth fishes, but their chemistry differs sharply. The useful split is between blackwater specialists, soft-water planted-tank species, adaptable farmed gouramis, and large robust forms.

For blackwater aquaria, reverse-osmosis water remineralised lightly is safer than chasing pH with bottled acids. Read water hardness, GH, and KH explained before attempting pH 4.5 water. For new setups, cycling a new aquarium matters even more than usual, because labyrinth breathing can hide early gill distress while ammonia still burns tissue.

Aquarium Husbandry

All anabantoid tanks need surface access. Leave an air gap, use a secure lid — see preventing labyrinth-fish escape jumps for lid and aquascape strategies — and avoid strong surface turbulence that destroys bubble nests. The air above the water should be warm and humid. Cold dry air repeatedly gulped by young bettas and gourami fry can damage delicate labyrinth tissue; trapped overheated air above 30 °C is also dangerous. A lid is not a sealed jar. Gas exchange and stable temperature both matter.

Filtration should be mature and gentle. Sponge filters, baffled outlets, and dense planting suit small species. Floating plants, Java fern, Anubias nana, and Cryptocoryne wendtii create shade and territorial breaks without demanding violent flow. Leaf litter is useful for peat specialists, but it must not be allowed to rot in an uncycled tank.

Tank dimensions matter more than advertised volume. A long shallow aquarium gives a betta or gourami more usable territory than a tall narrow column because these fish work the surface, the plant margins, and the upper third of the water. A 60 cm tank can be excellent for a pair of honey gouramis; a 60 litre cube with bare sides often produces more chasing because every retreat is visible from every other point. For licorice gouramis and wild bettas, visual barriers are not decoration. They are part of the behavioural equipment of the tank.

Current should be adjusted to the species. Paradise fish and climbing perch tolerate stronger movement than peat-swamp Parosphromenus, but even robust anabantoids do not need a torrent. The usual target is visible circulation without pinning floating plants against the glass or forcing the fish to swim continuously. Surface scum is best managed by plant thinning, feeding control, and slight surface movement rather than by violent agitation.

Stocking density should be conservative. Labyrinth fishes breathe air, but their waste is still processed by nitrifying bacteria, plants, and water changes. A single male fancy betta in 25–40 litres is not extravagant; it is the scale at which temperature, waste dilution, and swimming space become forgiving. A trio of honey gouramis belongs in 60–90 litres with cover. Pearl gouramis are better in 120 litres or larger, particularly if males are present. Kissing gouramis, giant gouramis, and climbing perch should be planned as large-specimen fish from the start, not upgraded after stunting has begun.

Tankmates should be chosen by behaviour, not by adult size alone. Harlequin rasboras, chili rasboras, and the rasboras guide give the closest regional matches for many small gouramis. Kuhli loaches work in warm soft tanks if the substrate is fine and the anabantoids are not tiny fry predators. Avoid fin-nipping barbs with fancy bettas and avoid boisterous livebearers in blackwater tanks.

Disease patterns are predictable. Fancy bettas suffer fin rot when kept in small uncycled volumes; use fin rot diagnosis rather than adding random antiseptics. Dwarf gouramis have a separate problem: commercial Trichogaster lalius lines have long-standing iridovirus issues, and newly imported fish can die despite acceptable water. Quarantine is not optional; see the quarantine tank protocol.

Breeding Modes in Aquarium Practice

Bubble-nest species are often described as easy to breed, which is true only for producing eggs. Raising fry is the demanding part. The pair should be conditioned separately or in a spacious planted tank, the spawning site kept calm, and the female removed if the male drives her hard after spawning. Once larvae hang from the nest, the male usually retrieves fallen fry until they become free-swimming. At that stage he may continue guarding, ignore them, or eat them depending on species and individual temperament. Small live foods are not optional; powdered dry food alone gives poor survival in the first week.

Mouth-brooders require the opposite approach. The brooding parent must be left alone. Betta macrostoma males commonly swallow eggs after netting, sudden bright light, or harassment by tankmates. Chocolate gourami females may hold a brood quietly while still joining the group, making it easy for an impatient keeper to interfere too soon. A brooding fish should not be chased into a trap unless the alternative is certain loss. Provide leaf litter, dim light, and several quiet feeding stations so non-brooding fish do not crowd the parent.

Fry development also explains the lid rule. As young anabantoids begin regular air breathing, the labyrinth organ is delicate. A cold draught across the surface after a water change can kill a spawn. Keep the water level low enough for the fry to reach the surface, cover the tank securely, and match replacement water for temperature and conductivity. In blackwater species, small daily water changes with identical chemistry are safer than large corrections.

Buying and Quarantine

The purchase decision often determines success before the fish reaches the tank. Choose alert fish with smooth scales, even breathing, intact mouths, and fins held naturally — clamped fins pressed tight against the body are a reliable early stress signal. Avoid bettas with severe body shortening, huge fins that prevent normal swimming, or metallic dragonscale lines with obvious eye scaling. Avoid dwarf gouramis from mixed import batches if the dealer reports unexplained losses. Locally bred dwarf gouramis and honey gouramis are materially better prospects than stressed, newly arrived farm fish.

Quarantine should last at least three to four weeks for most anabantoids and longer for delicate wild imports. Use a heated, covered, cycled tank with hiding places; a bare unheated box is not quarantine, it is another stressor. Observe appetite, faeces, fin edges, skin sheen, and breathing rhythm. Treat only what is diagnosed. Many labyrinth fishes tolerate medications poorly in very soft acidic water, so improving conditions and confirming the pathogen is safer than reflexively dosing a display tank.

Notable Species

• Siamese fighting fish (Betta splendens) — line-bred bubble-nester with spectacular finnage and real welfare problems in some strains.
• Wild betta imbellis (Betta imbellis) — quieter, shorter-finned member of the splendens complex for soft planted tanks.
• Wild betta macrostoma (Betta macrostoma) — Brunei paternal mouth-brooder for experienced keepers.
• Dwarf gourami (Trichogaster lalius) — beautiful but compromised by chronic farm-line viral disease.
• Honey gourami (Trichogaster chuna) — the best small community gourami when bought from healthy stock.
• Pearl gourami (Trichopodus leerii) — large peaceful lace-patterned species for quiet planted aquaria.
• Three-spot gourami (Trichopodus trichopterus) — hardy but males can dominate a community tank.
• Kissing gourami (Helostoma temminckii) — large, plant-grazing, and poorly suited to small aquaria.
• Sparkling gourami (Trichopsis pumila) and croaking gourami (T. vittata) — small sound-producing gouramis.
• Licorice gouramis (Parosphromenus spp.) — peat-swamp specialists requiring extreme soft acid water.
• Chocolate gourami (Sphaerichthys osphromenoides) — delicate maternal mouth-brooder from blackwater habitats.
• Paradise fish, banded gourami, giant gourami, and climbing perch illustrate the group's range from cool-water classics to public-aquarium animals.

Common Confusions

See Also

• Siamese fighting fish — fancy betta care, fin types, and ammonia-related disease.
• Honey gourami — the most reliable small gourami for calm planted tanks.
• Licorice gourami — peat-swamp chemistry and species-group caution.
• The Complete Rasboras Guide — Southeast Asian shoaling tankmates.
• Water Hardness: GH & KH Explained — essential chemistry for blackwater aquaria.
• Quarantine Tank Protocol — especially important for dwarf gouramis and imported wild bettas.