Minimum Tank Size: 29 Gallons (110 Litres)
Care Level: Moderately Hard
Water Conditions: 5.5-7.5 pH and Soft to Medium
Temperature: 73-82 °F (24-28°C)
Maximum Size: 5 inches (13 cm)
The moonlight gourami (trichopodus micrlepis), also known as the moonbeam gourami, is small labyrinth fish, that remains one of the most popular gouramis in the hobby today. It is native to Cambodia and Vietnam, and in recent years it has become established as an invasive species in Columbia and Thailand.
In the wild, it primarily tends to inhabit swamps and small bodies of water, but can also be found in nearly any environments that offers shallow and slow moving water. It prefers areas with dense vegetation, and it is most at home lurking among aquatic plants.
Moonlight gouramis are a labyrinth fish, which means that they have a lung like organ that allows them to breathe air. Because of this, they can survive in low oxygen environments that would kill almost any other fish, and can even survive for hours out of water (if they remain moist). Don’t be alarmed if you see your fish gulping in air at the surface, as this is normal behavior – even in well maintained, oxygen rich tanks.
The moonlight gourami is a small fish, and will usually grow to a maximum of 5 inches (13 cm) in the home aquarium. It’s not unusual for one to live 4 years or more in the home aquarium, and there have been some unconfirmed reports of them living past 6 years – though 5 years is far more realistic.
Moonlight gouramis need to be housed in at least a 29 gallon (110 litre) tank, and that size vastly increases if you plan on keeping more than one male gourami together. Males are incredibly territorial, and if you keep two males in a small tank together, you’ll usually end up with two fish with grievous wounds – which can often prove fatal.
Like with most other gouramis, it’s best to keep several females and one male in a tank. If you are dead set on keeping more than one male, you may need a tank as large as 75 gallons (340 litres), though you can sometimes get away with 45 gallons (205 litres) or larger.
It can also be difficult to find good tankmates for moonlight gouramis, and you have to balance the fact that they can mercilessly bully smaller fish, but they themselves fall prey to fin nippers. It’s best to keep them with fish close to their own size, while avoiding any that are known to nip fins.
When choosing a filter for these fish, you should always attempt to minimize any current in the tank. Moonlight gouramis do not do well in even moderate current, and they may end up being blown around the tank by a more powerful filter. Any tank containing this fish is a prime candidate for a canister filter, but you can also use hang on back filters if you lower the flow output, or plan your tank layout so that it deflects the current.
To make these fish comfortable, their tank should also be heavily planted. A heavily planted tank with open areas for swimming mimics their natural habitat, and will help them to feel at ease in the tank Some of the best plants to use are Amazon swords, hygrophila polysperma, water sprite and Java ferns.
In the wild, moonlight gouramis eat insects, invertebrates, algae and small amounts of plant matter. This diet should be recreated as closely as possible in the home aquarium, and this can be accomplished through regular feedings of a high quality flake food and live foods. One of the best foods that you can provide for them is New Life Spectrum Small Fish, which is hungrily devoured by moonlight gouramis.
When it comes to live foods, their favorites are mosquito larvae (illegal to culture to in some areas), bloodworms, blackworms, daphnia, adult brine shrimp and wingless fruit flies. If you don’t have access to live food, then you can provide them with frozen food, and they will happily accept frozen bloodworms, blackworms, daphnia and brine shrimp.
Breeding moonlight gouramis is relatively easy, and they will often breed on their own if you provide the right environment for them. The first thing that you need to do is make sure that you have a male and female. While both males and females look superficially similar, the females will have a more rounded belly than the males and will have a rounded dorsal fin, while the males have a pointed dorsal fin.
After you have ensured that you have a male and female, you need to be set up the breeding tank .The water should be soft and acidic, and it’s best to use a sponge filter, since the tank needs as little current as possible. It should also include significant amounts of floating vegetation, and barring that, you can provide fake floating plants or even the bottom half of a Styrofoam cup.
It’s absolutely key that some floating material be provided in the tank, since moonlight gouramis are bubblenest builders and males often need something that they can use as an anchor for the nest. The male will construct the nest out of hundreds of bubbles, and it’s not unusual to see nests that are 4-5 inches in diameter.
To start the breeding, lower the temperature of the breeding tank to the mid 70s, and introduce the male to the tank. Both the male and female should be conditioned at this point, feeding them a steady diet of live or frozen foods.
After a few days of conditioning, place the female in a location where the male can clearly see her. This can be done in a variety of ways, and the most common ways are either by using a tank divider, or by placing the females tank next to the males tank. You can also use a breeding net, but the small size of most commercial breeding nets just tend to stress out the female.
Once the female is in view of the male, spend the next few days slowly raising the temperature of the tank, until it reaches the low 80s. The male should begin constructing the bubble nest at this point, and if he doesn’t, try a large water change which will often trigger the behavior.
After the bubble nest has been constructed, the male will start to actively court the female. After this has commenced, release the female into the tank, and the courting will continue in earnest. Breeding will usually occur shortly after the female has been introduced to the tank, with the male herding the female under the bubblenest, where he will then curl around her.
Once the male has curled around her, the female will release her eggs, which will be fertilized by the male. After each mating, the male will spend several minutes scouring the substrate, carefully placing each eggs he finds into the bubblenest.
After several matings, the female should be removed as the male starts to guard the nest. Anything approaching the nest – the female included, will be attacked after the mating has been completed. The male will continue to guard the nest until the fry hatch and become free swimming. This usually takes about 5-7 days, and once they are free swimming, the male should be removed.
The fry should be fed three times a day, and will only accept infusoria or green water to begin with. They can then be moved onto baby brine shrimp, or commercially available fry foods. While it takes a bit more effort and planning, most aquarists prefer to use newly hatched brine shrimp.