Dwarf gourami

Red bars, blue bars, and a lot of color morphs

The dwarf gourami is one of the brightest fish in the store, and the males are territorial, so keep only one male per tank.

Trichogaster lalius, sold for years as Colisa lalia, comes from slow, weedy water in the Ganges and Brahmaputra basins of India and Bangladesh: ditches, ponds, and flooded rice fields. Adult males reach about 3 to 3.5 inches. Females stay a little smaller. With good care they live around four years.

Wild-type males have slanted red-orange bars over a pale blue body, as in the photo above. Farms have bred that into powder blue, cobalt blue, neon blue, and flame or sunset red fish. Females are silver-gray with faint bars and a rounded dorsal fin, and shops rarely stock them, so most tanks end up with a lone male. A male's dorsal fin is longer and comes to a point.

A 10 for one male, a 20 for company

One male dwarf gourami fits a cycled 10-gallon. On his own he is fine, and the calculator also passes him with a group of eight pygmy cories on sand. Finish the cycle before he goes in.

A 20-gallon is where he looks best. One male with eight harlequin rasboras and eight pygmy cories fits a 20 by the calculator's waste math. A male with two females works in a planted 20 long if the plants break up his view so he cannot chase one female all day. Two males need a 40 or more and a lot of plants, and even then it often ends with one hiding. The 20-gallon stocking guide has more mixes, and you can check your own in the stocking calculator.

Floating plants, warm air, and slow water

Dwarf gouramis are labyrinth fish. They gulp air at the surface as well as breathing through their gills, so keep the top open enough for them to reach and the air above it warm. A lid with the water an inch below it holds that air near tank temperature and stops the odd jump.

Set the heater around 77°F. They take 72 to 82°F and pH 6.0 to 7.5. A 50W heater covers a 10, and a 100W covers a 20 long in most rooms. Keep the flow gentle: a sponge filter, or a hang-on-back turned down so the surface ripples without churning.

Floating plants such as red root floaters or frogbit give them shade and the cover they want, and a low-tech planted tank with stem plants gives females somewhere to go. A male may build a bubble nest under the floaters and weave bits of plant into it. That means he is settled.

Iridovirus and how to buy a healthy one

Dwarf gourami iridovirus (DGIV) shows up again and again in farm-raised dwarfs. It has no treatment, and a fish that gets sick from it usually dies. Signs are a fish that stops eating, hangs near the bottom or in a corner, loses or darkens its color, and sometimes develops a swollen belly or open sores. Plenty of dwarfs never show it, but you cannot tell a carrier by looking.

You can improve the odds. Buy from a tank where every dwarf is eating and swimming, with no dead or listless fish in it. Ask the store to feed them while you watch. Skip fish with a sunken or swollen belly, clamped fins, or patchy color. A local breeder's fish are a better bet than a big shipment. Then run a four-week quarantine in a separate tank before the gourami joins anything else.

If you want the look with less risk, a honey gourami is smaller and calmer, and a pearl gourami is bigger and hardier. Neither has the same virus reputation.

Food and tank mates

Feed micro pellets or flake once or twice a day, and frozen daphnia, brine shrimp, or bloodworms a few times a week. They eat at the surface and in the upper water, so in a tank with fast tetras drop a second pinch at the other end. The feeding guide covers amounts.

Good company is small and calm: harlequin rasboras, ember or neon tetras, pygmy or peppered cories, kuhli loaches, otocinclus, and nerite snails. Skip bettas, which fight them for the surface, and tiger barbs, which go after the long feelers. Skip a second gourami of any kind in a tank under 29 gallons. Cherry shrimp are a gamble, because a dwarf gourami eats the babies and sometimes picks at the adults.