Paradise Fish

For a single fish or a one-male-plus-two-female group, provide an aquarium of at least 80 x 30 cm footprint (roughly 75 litres / 20 US gallons); never house two males together unless the tank is very large (115 litres and up) with dense planting to break lines of sight. Use a soft, dark substrate (fine sand or smooth rounded gravel) which shows off their colours. Furnish heavily with live or silk plants, driftwood, and leaf litter to create territories and hiding spots, and leave calm, planted surface areas for bubble-nest building. A tight, gap-free lid is essential: they jump, and they must still be able to reach the surface to breathe air.

Paradise fish are insectivores/carnivores. Feed a staple of good-quality micro-pellets or flakes formulated for gouramis/bettas, and offer live or frozen protein foods several times a week: daphnia, brine shrimp (Artemia), bloodworm, mosquito larvae, white worm, and grindal worm. A little spirulina-based food adds variety. Feed small amounts once or twice daily, only what is eaten in a couple of minutes. AVOID: overfeeding (the leading cause of illness and fouled water), an all-dried-food diet with no live/frozen variety, mammalian meats such as beef heart which they digest poorly, and any copper-containing or expired foods.

This is a cool subtropical species, so aim for an unheated, room-temperature tank. Seriously Fish gives a natural range of 10 to 22 C (FishBase cites 16 to 26 C); a safe, stable indoor keeping range is roughly 16 to 24 C. They tolerate cool spells well and actually benefit from a slightly cooler winter, but sustained temperatures above 26 to 28 C stress them and shorten their lives, so heat is the real enemy, not cold. Water: pH 6.0 to 8.0 (ideal 6.5 to 7.5); hardness roughly 5 to 20 dGH (90 to 357 ppm); ammonia and nitrite 0 in a fully cycled tank. Filtration should be gentle. A sponge filter or a baffled internal/hang-on-back filter is ideal, as they dislike strong current. Standard subdued aquarium lighting suits them and no UVB is needed. Because they breathe air at the surface, keep the room reasonably warm above the water line to avoid chilling the labyrinth organ, and do regular partial water changes to keep water quality high.

Best kept as a single specimen, or as one male with two or more females in a spacious, planted tank so the male's attention is divided and no single female is harassed. Multiple males will fight, often to injury, and should not be combined except in large, heavily broken-up aquascapes. In a community, choose fast, robust, similarly-not-shaped mid-water or schooling fish and avoid other labyrinth fish, slow long-finned fish (fancy guppies, bettas), fin-nippers, and anything small enough to be eaten. Sexing is straightforward once mature: males are larger and more intensely coloured with distinctly longer, pointed, extended rays on the dorsal, anal, and tail fins; females are smaller, duller, with shorter rounded fins and a fuller belly when carrying eggs.

Being an intelligent, curious anabantid, the Paradise fish thrives on a complex, planted environment it can patrol and claim. Dense planting, driftwood, and leaf litter give it territory to explore and defend and reduce stress and aggression. A varied diet with live foods that trigger natural hunting behaviour is excellent enrichment. A calm, planted surface encourages males to build and tend bubble nests, one of the most rewarding natural behaviours to observe. Gentle, indirect room activity and a stable routine suit them; avoid startling them, as they are alert and reactive.