The temperament of the Moonlight Gourami is often debated, but one thing aquarists can agree on is the intoxicating beauty of this fish!
The Moonlight Gourami Trichopodus microlepis (previously Trichogaster microlepis) is a stunning fish, and even more so as it matures. It has a silver body with a wonderful iridescence that becomes touched with a pastel green hue in the adults. Males have an orange to red coloration to the pelvic fin, but there are no other color markings on its body and its scales are very small. Together these create its illustrious sheen, and even in a dimly lit tank this fish has the soft glow of moon light.
This gourami is aptly named for this wondrous glowing effect. In its scientific name the term ‘microlepis‘ actually refers to its small scales, and a second common name it is known by is the Moonbeam Gourami. In Thailand it is called Pla Kadi Nang, while they call other gouramis in this genus Pla Kadi. The term “Nang” was attached because it means wife or woman and they thought this silver fish was a female form of the Blue (Three-spot) GouramiTrichopodus trichopterus.
This is truly a magnificent beauty that can make quite an impact when displayed in a well thought out tank. Its shimmering colors are complemented by an unusual shape and form. What’s unique to this species is a distinct concave slope to its head and much longer ventral fins than seen on other gouramis. These filaments, usually orange on the male, will intensify and turn red during spawning. The eyes too are an interesting feature, with a red to orange iris that seemingly watches your every move.
Features of this fish include it being a Labyrinth fish. Labyrinth fish differ from all other fish species because they can breathe atmospheric oxygen. Another labyrinth fish characteristic is that of being a bubble nest builder for reproduction and care of the fry. This male will build a huge nest of loose bubbles and pieces of vegetation. Whole water plants may be ripped out and used, with the bubbles helping to hold it together. There are reports of nests as large as almost 10″ (25 C) in diameter. When spawning, eggs that don’t float up to bubble nest will be collected by the male and spat into his nest, then he will continue to guard them until they hatch.
All together this unique gourami has a delicate appearance, yet swims gracefully through its planted waters. It is an excellent aquarium fish thats great for people with some fish keeping experience. It is a good size, being capable of reaching a length of 7 inches (18 cm), so it’s not surprising that it is appreciated as food fish by the locals in its native countries. However it will generally attain only about 5 or 6 inches (12 – 15 cm) in most aquariums. With their adult size they need to be housed in a roomy aquarium of 40 gallons or more.
They should also be kept in a planted tank, but they tend to have a love hate relationship with aquarium plants. Even though plants are to their liking and make them comfortable, they will tend to chew on them. Very fine-leaved plants will be damaged quickly, so thick-leaved, hardy plants will need to be used. Artificial plants can make a handy substitute.
Like many Labyrinth fish, aquarists just can’t agree about the disposition of the Moonlight Gourami. Individuals of this species are for the most part super mellow and timid, but some are boisterous and cantankerous. A few fall somewhere in between. Careful observation at the fish store may give you a clue as to which personality type you’ve got. Most people learn to love theirs, either way. The best tankmates for this fish are those with a similar temperament, just make sure other fish aren’t so small that they get snacked on. Most medium size, peaceful fish work well with the exception of fin nipping types.
For Information on keeping freshwater fish, see:
Freshwater Aquarium Guide: Aquarium Setup and Care
- Kingdom: Animalia
- Phylum: Chordata
- Class: Actinopterygii
- Order: Perciformes
- Family: Osphronemidae
- Genus: Trichopodus
- Species: microlepis
- Aquarist Experience Level: Intermediate
- Size of fish – inches: 7.0 inches (17.78 cm)
- Minimum Tank Size: 40 gal (151 L)
- Temperament: Peaceful
- Aquarium Hardiness: Moderately hardy
- Temperature: 77.0 to 86.0° F (25.0 to 30.0° C)
- My Aquarium – Enter your aquarium to see if this fish is compatible!
Habitat: Distribution / Background
The Moonlight Gourami Trichopodus microlepis (previously Trichogaster microlepis) was described by Günther in1861. It is found in Asia, originating from the tropical Far East in Vietnam, Cambodia and Thailand. it has also been introduced outside of its native range with feral populations found in Singapore and in Colombia, South America, introduced as escaped fish from breeding facilities.
This species is listed on the IUCN Red List as Least Concern (LC). It has a wide range and diverse habitats and is a common species across Southeast Asia. It is sometimes market as a fresh fish, and eaten by the locals. The fish available in the hobby are rarely wild specimens anymore. The majority of the ones for sale are commercially bred in the Far East and Eastern Europe. Another common name it is known by is the Moonbeam Gourami.
There has been a recent change to its generic name. A paper by Myers back in 1923 resulted in a taxonomic misinterpretation which was only recently brought to light. At the time of his paper, the generic name Trichogaster was adopted for the larger eastern species of gourami from Southeast Asia. Recently the interpretation by Myers came under review and this previous taxonomical structure was revisited and then restructured. The result is that the species which had been placed under Trichogaster have now been reverted back to Trichopodus, as per Topfer and Schindler in 2009, and Tan and Kottelat in 2009.
In nature these fish occur in lowland ponds, bogs, swamps, and lakes and are also common in the floodplain of the lower Mekong. They are primarily found in shallow, slowly flowing or standing waters, that are heavy with plants in the water and along the margins. They are omnivorous in nature and feed on zooplankton, crustaceans, and aquatic insects.
An interesting behavior, similar to that of the Archer FishToxotes jaculatrix, found in both the Trichopodus and Trichogaster species is that they have been observed catching their prey by squirting water. They do this by aligning themselves diagonally in the water to watch for prey above. Then with sudden contractions of their mouth cavity, they will squirt drops of water at the prey, knocking it off its perch into the water, where it is quickly snapped up by the fish. It has been observed in these fish mostly right after breeding.
- Scientific Name: Trichopodus microlepis
- Social Grouping: Groups – In nature these fish live communally with other peaceful species.
- IUCN Red List: LC – Least Concern
The Moonlight Gourami has a compressed, rather elongated body covered with small scales and a distinct concave slope to its head. One of its most notable characteristics are its ventral fins. These are very long threadlike filaments, longer than those of any other gourami species, and extremely sensitive. Unfortunately a great many of these fish develop deformities, which is thought to be because they have been heavily interbred.
Like all other gouramis this fish can breath air, generally gulping it at the water’s surface. It has a special ‘labyrinth organ’ which acts like a lung which enables it to survive in oxygen-depleted waters. It is capable of reaching up to 7 inches (18 cm) in a large tank, but generally only reaches about 5 or 6 inches (12 – 15 cm) in most aquariums. Their average lifespan is about 4 to 6 years with good care.
The body color of this gourami is an even silvery sheen created by its very small scales. It is tinted with a pastel green iridescence on the back, which becomes apparent as it ages, and the eye has a red to orange iris. The male has orange or red pelvic fins, while the pelvic fins of the females are colorless or yellow. Younger gouramis lack the green and silver iridescent hues.
- Size of fish – inches: 7.0 inches (17.78 cm) – This fish is capable of 7″ (18 cm) in a large tank, but generally only reaches about 5 or 6″ (12- 15cm).
- Lifespan: 4 years – The average lifespan is 4 – 6 years with proper care.
Fish Keeping Difficulty
This gourami is a hardy and stunning fish, but is suggested for a fish keeper with a moderate amount of experience. They need a large, planted aquarium that has fairly stable water conditions. They will easily take most commercially prepared foods but are slow swimming and eat slowly. They also have varying temperaments within the species. Some are very timid and peaceful and will get easily stressed with overly active companions, while others are more boisterous and even bullying in nature. The tank requirements, slow moving habits, and variable temperaments can make matching tankmates rather difficult.
- Aquarium Hardiness: Moderately hardy – These fish are very willing to adapt to most water conditions, as long as the conditions remain stable.
- Aquarist Experience Level: Intermediate
Foods and Feeding
The Moonlight Gouramis are omnivorous, in the wild they feed on zooplankton, crustaceans, and aquatic insects. In the aquarium these fish will usually happily eat prepared flake and tablet foods, as well as live foods.They particularly enjoy chasing after live worms (blood or tubifex). Be sure a substantial part of the diet is a high quality flake food to meet their vitamin requirements. Supplementation can include white worms, blood worms, brine shrimp, or any other suitable substitute. Fresh vegetables and vegetable tablets can be offered as well. Generally feed once or twice a day.
- Diet Type: Omnivore
- Flake Food: Yes
- Tablet / Pellet: Yes
- Live foods (fishes, shrimps, worms): Some of Diet
- Vegetable Food: Some of Diet
- Meaty Food: Some of Diet
- Feeding Frequency: Daily – Generally feed once or twice a day.
These are hardy fish but because they eat a lot, water quality must be maintained. Being on top of your tank maintenance is very important for these fish to be at their best. If the Moonlight Gourami is spending a lot of time at the surface gulping air, you are overdue for a water change. Although the labyrinth organ allows the fish to survive in oxygen depleted water, it is a common misconception that this makes water changes unnecessary. This is hardly the case as these fish will suffer the same tissue damage from built up toxins as any other fish. Regular water changes are a must with 25% weekly being recommended.
- Water Changes: Weekly – Weekly water changes of 25% are recommended.
The Moonlight Gouramis will swim in the middle regions of the tank. They enjoy an aquarium that is roomy but it is important they have unobstructed access to the surface. As Juveniles this fish can be housed in a 20 – 25 gallon aquarium, but adults will need 40 gallons or more. It’s desirable to keep the tank in a room with a temperature as close as possible to the tank water to prevent damaging the labyrinth organ. Provide a good filtration system that produces a gentle flow while also efficiently removing waste. This fish will be bothered by a strong current in the tank, especially if the tank is small. Air stones can help provide well oxygenated water.
These gouramis will show their colors best on a dark substrate. The tank should be well planted with some hiding places as well as areas to swim freely. Hiding places will give this gourami an additional sense of security. But though a planted aquarium makes them comfortable, they tend to abuse their plants. Albeit they are far from leaving a trail of shredded plants in their wake, this is simply not a fish for those striving for planted perfection. They are known to chew on plants, even uprooting them. Very fine-leaved plants can quickly be damaged so a good compromise is to use thick-leaved, hardy plants. The best plants are sturdy varieties like the Java Fern or some of the Rosette varieties like the vallisnerias and anubias species. Artificial plants can make a handy substitute.
- Minimum Tank Size: 40 gal (151 L) – Juveniles can be kept in a 20 – 25 gallon aquarium, but adults need more space.
- Suitable for Nano Tank: No
- Substrate Type: Any
- Lighting Needs: Moderate – normal lighting
- Temperature: 77.0 to 86.0° F (25.0 to 30.0° C) – Keep the surrounding room temperature consistent with the water temperature to avoid causing trauma to the labyrinth organ.
- Breeding Temperature: 80.0° F – They will breed with temperatures at about 80 – 85° F (26 – 28° C).
- Range ph: 6.0-7.8
- Hardness Range: 2 – 25 dGH
- Brackish: No
- Water Movement: Weak – This fish doesn’t like a strong current in the tank, especially if the tank is small.
- Water Region: Middle – These fish will usually inhabit the middle regions of the aquarium.
Even though they get quite large, rouge individuals aside, the Moonlight Gouramis are generally good community fish. They can be kept singly, in pairs, or groups it the aquarium is large enough. If kept in a group make sure there are plenty of hiding places to keep one or more of the individuals from being bullied.
In a large tank with plenty of hiding places other Labyrinth fish of the Trichopodus and Trichogaster species may be good tankmates. Yet because this gourami may become territorial with age, particularly with other gouramis, so you have to keep an eye out. Males will fight amongst theirselves too, if not enough room for their own territory. The females are usually more sedate than the males.
Very small tankmates should be avoided as they may get eaten. Fin nippers must also be excluded from tanks that house gouramis because they just can’t resist those trailing pelvic fins. Other good tankmates include loach species like the Redtail BotiaYasuhikotakia modesta, some of the catfish species like the Corydoras and loricariids, as well as Angelfish. Some of the peaceful barbs also work well, but avoid those that are notorious fin nippers like Tiger Barbs and Clown Barbs.
- Temperament: Peaceful – This fish is generally peaceful though personalities tend to go either way as they mature, with individuals being are either very passive or extremely cantankerous.
- Compatible with:
- Same species – conspecifics: Yes – Males will display territorial type behavior when breeding.
- Peaceful fish (): Safe
- Semi-Aggressive (): Monitor
- Aggressive (): Threat
- Large Semi-Aggressive (): Threat
- Large Aggressive, Predatory (): Threat
- Shrimps, Crabs, Snails: May be aggressive
- Plants: Monitor
Sex: Sexual differences
The male is more slender than the female and has longer more pointed dorsal and anal fins. The male’s pelvic fins will be flushed with a reddish orange, where as the females will have colorless or yellow pelvic fins. The ventral fins are usually orange on the male, but will intensify and turn red during spawning.
Breeding / Reproduction
Like most fish in this family, the Moonlight Gouramis are bubble nest builders. This fish is somewhat of a challenge to breed, but not impossible. Their bubble nest consists mostly of water plants with loose bubbles helping to hold it together. Nests for this species have been reported to be as large as almost 10″ (25 C) in diameter and about 6″ (15 cm) thick. The part that’s used is a large concentration of bubbles in the center.
A pair will be most likely to spawn if the tank is roomy and well planted with a good sized surface area and a temperature to their liking. They should be well conditioned with small offerings of live and frozen foods several times a day. When well fed, females should begin filling out with eggs, appearing very plump. In breeding mode the males ventral fins will turn red and he will begin to build a large bubble nest at the surface.
It is best to provide a breeding tank of about 20 gallons or more, and keep the water level low, at about 6 – 8″ (15 – 20 cm). It should have slightly soft water and a temperature at between 80 to 85° F (28° C). An air-powered sponge filter can be added but the tank but any current should be minimal. They need some floating plants like Ricca, or stem plants grown to the surface. These will promote a feeling of security in the fish and help keep the bubble nest in place. Adding bushy plants as well will provide hide places for the female.
Once the nest had been built the male will begin a courtship display to entice the female to spawn. The male will begin swimming around the female trying to draw her underneath his nest. Once the female is receptive, she allows the male to wrap his body around hers and then expels a few eggs. The male will immediately fertilize them. As the eggs float upwards the male shepherds them into the nest and the pair will then spawn again. Spawning may last up to 2 hours. These fish have known to produce anywhere up to 2000 eggs though usually its between 500 – 1000. After spawning the male will chase off any fish that approach, and that may including the female. It is usually advisable to remove the female at this time, or the female can be kept in the tank as these males are often less aggressive than other Labyrinth fish.
The male will tend the nest and guard the eggs until they hatch. The eggs will hatch in 1 to 2 days and the fry become free swimming in about 2 more days. At this time both the parents should be removed or they might eat the fry emerging from the nest. Free swimming fry can be fed infusoria or a liquid fry food until they are large enough to eat baby brine shrimp. The fry are very sensitive to water conditions, so water changes should not be done until they are about a half and inch in length or so. See the description of anabantoid breeding techniques in: Breeding Freshwater Fish: Anabantoids. Also see Fish Food for Fry for information about types of foods for raising the young.
- Ease of Breeding: Moderate
Moonlight Gouramis are hardy so disease is not usually a problem in a well maintained aquarium. Some diseases they are prone to are bacterial infections, constipation and Hole in the Head if good water quality, nutrition, and maintenance is not provided. With any additions to a tank such as new fish, plants, substrates, and decorations there is a risk of introducing disease. It’s advisable to properly clean or quarantine anything that you want add to an established tank prior to introduction, so as not to upset the balance.
These fish are very resilient but knowing the signs of illness, and catching and treating them early makes a huge difference. An outbreak of disease can often be limited to just one or a few fishes if you deal with it at an early stage. The best way to proactively prevent disease is to give your fish the proper environment and a well balanced diet. The closer to their natural habitat the less stress the fish will have, making them healthier and happy. A stressed fish will is more likely to acquire disease. For information about freshwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.
The Moonlight Gourami is readily available both in stores and occasionally online, and is reasonably priced.
- Animal-World References: Freshwater Fish and Plants
- Trichogaster microlepis (Günther, 1861) Moonlight gourami, Fishbase.org
- Trichopodus microlepis, The IUCN Red List of Threatened Species
- Trichogaster lalius Dwarf Gourami, Seriously Fish, 2013
- Dr. Rudiger Riehl and Hans A. Baensch, Aquarium Atlas Vol. 1, Publisher Hans A. Baensch, 1991
- Joseph S. Nelson, Fishes of the World, Wiley, 2006.
- Greg Jennings (Editor), 500 Freshwater Aquarium Fish, Firefly Books Ltd, 2006.
- Glen S. Axelrod, Brian M. Scott, Neal Pronek, Encyclopedia Of Exotic Tropical Fishes For Freshwater Aquariums, TFH Publications, 2005
- David Alderton, Encyclopedia of Aquarium and Pond Fish , DK Publishing, Inc., 2005.
- Hans-Joachim Richter, Gouramis and Other Anabantoids, T.F.H Publications, Inc., 1988
- Dr. Herbert R. Axelrod, Aquarium Fishes of the World, TFH Publications, 1998