Moonlight Gourami (Moonbeam Gourami) Fish Species Profile

The common name moonlight gourami describes this peaceful labyrinth fish quite well. Its body is silver-colored with a slightly greenish hue that is not unlike the soft glow of moonlight. Like all labyrinth fish, Trichogaster microlepis has a special organ that allows it to breathe air directly. Because of this labyrinth organ, it is not unusual to see it go to the surface to gulp air. The ability to breathe air allows these fish to survive in situations with very low oxygen. In fact, if this fish remains moist, it can actually survive out of water for up to several hours. The concave slope of the head in the moonlight gourami distinguishes it from other gourami species.

Characteristics

Origin and Distribution

The moonlight gourami originates in the tropical areas of Vietnam, Thailand, and Cambodia. It prefers still or slowly moving waters with plenty of vegetation such as ponds, bogs, swamps, and lakes. The fish are also found in the floodplains of the Mekong River. As it has been bred in captivity in various parts of the world, it has escaped from breeders and become an invasive species in both Singapore and Columbia. This species is also farmed for food in Southeast Asia. Most moonlight gouramis intended for the aquarium market are bred in captivity.

Colors and Markings

The moonlight gourami is long and flat; its head has a concave curve. Its ventral fins boast long filaments that are sensitive to touch; males' pelvic fins are red while females' pelvic fins are yellow or colorless. It has small, silvery scales which, as it matures, develop a pretty greenish iridescence. The eyes are red or orange.

Tankmates

Moonlight gouramis can be kept in pairs or groups in a community tank, so long as there are hiding places for the least aggressive in the group which is sometimes bullied. Other tankmates can include other labyrinth fish and larger species such as redtail botia, corydoras, and angelfish.

Avoid fin-nipping species such as clown barbs, as the moonlight gourami has long filaments on its fins which are very tempting. Even under ideal conditions, this is a fish that tends to be timid. It should be kept only with non-aggressive tankmates.

Moonlight Gourami Habitat and Care

Sturdy vegetation such as Java fern and Vallisneria are excellent choices for habitat. Although it makes a beautiful addition to a community tank, don't be surprised if it hides regularly. Although undemanding about water conditions, it does best in soft acidic water. Because it is so tolerant of less than perfect water, it is a good beginner fish. However, the water should be changed regularly to maintain good health.

Moonlight Gourami Diet and Feeding

The moonlight gourami will eat flake, frozen, and live foods. Serving a good variety of live and flake foods will help ensure optimum health. If you have a community tank with other large fish, make sure they aren't scaring the moonlight gourami away from the food. This is a timid fish that will not fight for its dinner, even if it is very hungry.

Gender Differences

Females are wider than males and have more rounded anal and dorsal fins. Males can be identified by the orange to red coloration of the pelvic fins, as well as the long dorsal fins that end in a point. In females, the pelvic fins are colorless to yellow, and dorsal fins are shorter and rounder. ​During spawning, males' ventral fins turn from orange to red. 

Breeding the Moonlight Gourami

The moonlight gourami is an egg layer that builds a bubble nest as do most labyrinth fish. Breeding of this fish is both easy and interesting. Provide a separate breeding tank, as other fish will consider these eggs and small babies (fry) a tasty snack.

The ideal breeding tank has very soft water that has been reduced to a depth of about six inches. The pH should be slightly acidic, and the temperature should be raised to at least 80 Fahrenheit over a period of several days to trigger spawning. Use dark gravel and provide plenty of floating plants for building the bubble nest. Feeding the breeding pair live foods before attempting to breed them will increase your chances of success.

The male begins the spawning process by carefully preparing a bubble nest. He then begins to court the female under it. This courtship dance is a fascinating display that should not be missed. Spawning culminates in the male wrapping itself around the female. While in this embrace, the male turns the female onto her back, which triggers her to release eggs. Up to 2,000 eggs may be laid during the spawning, which the male fertilizes as they float up to the nest. In the safety of the bubble nest, the eggs incubate for two to three days before hatching.

Once the eggs hatch, the fry must be fed very tiny foods several times daily. Most losses of fry are due to a lack of adequate food or too low water temperature. Live foods such as daphnia, artemia, and rotifers, are ideal. However, very finely chopped lettuce, banana skins, and finely ground flake food can be used to feed the young (and are usually easier to find). Keep the water temperature in the low to mid-80's while the fry (tiny juveniles) are growing.

More Pet Fish Species and Further Research

The many gourami species are fun additions to any tank as they utilize the upper layers of the water. If you’re interested in similar species, check out:

• Dwarf Gourami Fish
• Blue Gourami Fish
• Pearl Gourami Fish

Check out additional fish species profiles for more information on other freshwater fish.