The giant gourami (lat. Osphronemus goramy) is the largest fish from all gourami species kept in tanks. In the wild, it can grow up to 60 cm (24 in) long and even larger, according to some data. In tanks, it grows a bit smaller, about 40-45 cm (18 in), but still, it is a very large fish.
Habitat in the wild
They initially used to dwell in Greater Sunda Islands (Sumatra, Java, Borneo, etc.). The fish is still bred for sale in various Asian countries (especially in South-East Asia and South Asia) and Australia.
In many countries, including Australia, the giant gourami is bred as harvested species. In Indonesia and Malaysia, it is of high significance in this respect. The fish is tasty, and it has large bones. Gourami is always available in restaurants, and the fish is used for cooking lots of various dishes especially grilled fish, and it is served with sweet-and-sour sauce. The fish is quite expensive as well. It is extremely popular in Javan cuisine – on Java island, almost every village has its artificial pond with gourami bred to cook them.
In the wild, the giant gourami dwells in large rivers with slow flow, lakes, and bogs, including those with brackish water. Giant gourami prefers shallow waters with lots of water plants. The fish can breathe humid air and can survive without water for rather a long time. They are mainly plant feeders, but also they feed on insects and small fishes. As the fish is an active plant feeder, it is used to fight against weed plants in ponds.
Floods that happen from time to time due to the rivers’ overflow in the rainy season promote fish migration. These are some of the few freshwater fishes that are resistant to brackish water. In the wild, some small populations were found in ponds with brackish water.
They have a special lung-like labyrinth organ that helps them to survive in ponds poor in oxygen. They gulp some air on the water surface and, with the help of this organ, direct the atmospheric air right to their blood flow.
|Scientific Name||Osphronemus goramy|
|Common Name||Giant gourami; kaloi fish|
|Ease of keeping||Medium|
|Lifespan||20 years and more|
|Tank size||800 liters (175,98 gallons) and more|
|Temperament||Peaceful to large fishes|
|Tank type||Community of large fishes|
|Temperature||optimal 22–30 °C (72–86 °F)|
|Water hardness||9–20 dGH|
|Size||Up to 70 cm (28 in)|
This is fish with a wide and flat body. Its standard length is twice larger than its body height. The total length of the giant gourami body, including its tail fish, can reach 70 cm (28 in), but in tanks, as a rule, it’s no larger than 45 cm (18 in) long.
The young fish has a pointed snout and about 8-10 stripes on its body. As the fish grows, its coloring gets paler, and the head becomes disproportionately large as well as a nuchal hump appears on its head.
The abdominal fish fins have one coarse spine and 5 soft rays, the first of which has transformed into a long, pliant string that acts as a tactile organ. The dorsal has 11-14 coarse rays and 12-14 soft ones; the anal fin has 11-10 coarse and 20-23 soft rays.
The giant gourami coloring varies from pale yellow to golden-yellow with a silvery tint and transverse light-blue stripes on its body. Adult coloring gets paler in time, and it becomes completely white, rosy, or gray at the end. There are artificially bred colorings: albino, golden (with the body color varying from yellow to golden), black (with the gray-colored body and red fins), and silvery.
Young fish look rather appealing. They have sharpened snoot, reddish fins, flattened head, and nice coloring. There are 8-10 lateral stripes which color varies from silver-blue to almost black, and they enhance the contrast with the greenish-brown body. With age, the coloring gets darker, the fish body becomes taller, and the stripes disappear.
It gets its full adult size at the age of about 4-5 years old. Provided with proper care, the giant gourami lifespan is over 20 years.
Difficulties in keeping
This is a fish which, in general, isn’t difficult to keep. There is only one issue – its size. Keeping giant gourami can be recommended for experienced aquarists who have very large tanks, powerful filters since the fish is a gluttonous one and produces lots of organic waste correspondingly. The fish is interesting due to its temper, which shows some signs of intellect and long life experience – the fish lifespan is often longer than 20 years.
Some time later, you stop taking them as just large fish since they will turn into nice pets with their own temper and perception. They will recognize their owner and let him touch them.
Care and keeping in a tank
The biggest problem here is tank capacity. The adult kaloi fish requires a tank of 800 liters capacity and more. Even provided with not perfect tank conditions, they can grow from 7,5 cm to 50 cm long in four years. The fish’s high growth rate can become a problem for an inexperienced aquarist since juveniles can be easily confused with those of chocolate gourami, which grows smaller.
Young giant gourami may live in a comparatively small tank for some time. For a group of fish up to 10 cm (4 in) long, a 400 liter (90 gals) tank will do. There, a group of 5-6 youngsters may live up to reaching the size of about 20 cm (8 in).
To make sure that the juveniles you bought become large fish, the tank should be really spacious. Or you should replace it with the larger as the tank dwellers grow. For a couple of adult giant gourami, a tank 2 meters (79 in) long, 70 cm (27.5 in) wide, and high is the optimal one.
The presence of labyrinth organ quite often leads to a common mistake that the tank water doesn’t require often renews, which is complete nonsense. The fish in such water often suffers from tissue injuries since if ammonia concentration in water becomes too high, they may die because of poisoning.
Regular water renew is a must. It is recommended to renew 25% of the total tank volume every week.
The latter is usually a problem because giant gourami leaves lots of organic waste, and only several powerful filters can deal with such a load as well as regular water renew (25 — 50%of the total tank volume) in a must once a week.
Giant gourami can dwell at a wide range of tank parameters. That’s why there only two parameters that are of key importance here: a sufficient amount of free space and clean water.
At that water hardness can be up to 30 dGH, pH 6—8, the temperature can vary from 18 to 32°C (65-90 °F).
Water filtration and aeration
Due to the giant gourami size and appetite, they create a significant biological burden for a tank. For this reason, the latter requires an efficient and effective filtration system.
If filtration is organized properly, you can decrease water renews to once in two weeks. However, in this case, you’ll have to renew almost half of the volume. You should combine water renewal with the bottom siphonage (if there is a bottom substrate in the tank).
Also, you should consider that the fish doesn’t like water flow; thus, filter and pump outputs should be directed so that there are some places in the tank without water flow.
However, aeration isn’t a must in this case. They like all climbing perch species, use atmospheric air for breathing, getting to the water surface from time to time.
Tank setup: decorations and plants
The giant gourami is large and active, and it requires a minimum of tank decorations and plants to make sure that it has room to swim. Use large stones and snags as shelters for the fish. Tank plants have to be highly enduring with coarse leaves, for example, Anubis, since for giant gourami, any plant is food.
There is no point in decorating a tank with live plants since they’ll be eaten sooner or later. In tropics, these fishes are often put in the ponds and lakes on purpose to decrease the amount of aquatic vegetation in them.
Since the giant gourami is not compatible with aquatic flora, to decorate the tank, it may be enough to put some dark-colored substrate or several large snags and smooth stones.
It’d be good to create a shelter for the fish in a tank, where they can hide from both humans and their relatives. The water surface can be partially covered with fluctuant. For this purpose, it’s better to use some fast-growing species (like amazon frogbit) since they will eat the plant from time to time.
In terms of tank decorations, we advise using large stones. They should be as settled as possible. Snags shouldn’t have any sharp stare knots because the fish can wound itself if it gets scared.
Like all climbing perch, giant gourami has to get to the water surface from time to time to get another gulp of air. For this reason, between the water surface and the tank cover, there should be enough free space. Considering the tank dwellers size, the cover glass should be especially thick so they won’t break ut if they decide to jump out of the tank.
Compatibility and tank mates
While the juveniles may demonstrate aggression, adults are very calm and quiet fish, and due to this, they are very often used for displaying in large exhibition tanks. At that, their aggression has periodic nature. Dominating species may haunt actively for several minutes some of its relative and some time later peacefully swim side by side with it.
The giant gourami is ok when alone in a tank, or it can live as a couple (male and female). Young fish species often fight with each other, but they become calmer as they grow. However, adult males still can demonstrate aggression towards their rivals.
The best result is achieved when keeping them in a group. The dominating species become less aggressive in this case, the rest of the fish become calmer and demonstrate more natural behavior. However, quite a spacious tank is required for a group of 4-5 adult species
The giant gourami size and habits allow it to feed on small fishes, so you can keep with small tank mates only if they are supposed to be its food. As a rule, this fish is kept together with large cichlids or catfishes.
As for the tank mates, giant gourami is more tolerable to other large species than their kind. Considering this, many relatively large and active fishes will do as their tank mates, but their size should be large enough not to become gourami food.
Large cichlids (oscar, blood parrot, flowerhorn, green terror), catfishes (pleco, redtail catfish), loaches (clown loach, dojo loach), silver arowana, motoro, silver dollar, pacu will do in this case.
In the wild, the giant gourami diet consists of various aquatic plants, small fish, amphibians, earthworms, and even carrion sometimes. The fish eats all types of food. The thing is about its amount. Giant gourami is a large fish, and it requires corresponding amounts of food. There is a peculiarity – if the fish is bought as an adult (they live for a very long time), ask about its usual diet. Otherwise, it may refuse to eat the food you give since it’ll be new and unknown to the fish.
For example, initially, the fish was fed only with protein food (worms, small fishes, insects, etc.), it’ll be quite difficult to start feeding it with artificial food, and thus keeping it will become rather costly.
The easiest thing to do is to get a young fish and feed it according to your possibilities because the fish is undemanding. It’ll eat almost everything that you offer. Some giant gourami owners consider that only a plant food diet is enough for it, which is a completely wrong idea.
Indeed, the adult fish fancies greenery and fruit, but animal protein is required for proper balanced development, especially for young fish. Shellfish, crustaceans, calamari, insects, earthworms are the source of protein for young fish.
Besides the food mentioned above, you can feed them with non-fat fish, bread, boiled potatoes, and other vegetables. It’s not recommended to feed them with beef heart and mammal meat because the fish can’t digest it properly.
To keep them in good shape, you should add into their diet some high-quality flakes and specially balanced pellets for KOI or large cichlids. The fish quickly gets used to taking food from your hands, which is quite convenient from the point of view of the tank water purity since the food goes right into the fish mouth, without getting in the water.
The main concern is not to overfeed them because it may cause the fish death. You should feed them once a day to let the food digest completely.
When catching the food, they produce specific chewing noises. Due to the special construction of their labyrinth organ, they can’t swallow large food pieces only after the second or third attempt, after taking another deep breath, they can do it.
Gender differences: male vs female
The male giant gourami has a high forehead, sharpened dorsal, and darker body coloring that becomes almost black during the spawning period. The female fish has rounded fins and fleshy lips. At the age of eight months, being 12 cm (5 in) long, they can start breeding.
Giant gourami is an egg-laying fish. Before spawning, the male fish builds a nest from bubbles, water plants, and plant rubbish. The eggs are kept inside the nest attached to water plants in it. Provided with a large spacious spawning tank breeding the fish is not challenging. However, the spawning tank size very often becomes an insurmountable problem.
In the wild, the nest-building process usually occurs in April-May; however, the fish can spawn all year-round. The process itself takes 8-10 days. The male usually builds a nest among canes. It’s reasonable to keep the breeders separately before spawning. The spawning tank should be shielded from direct sunlight to prevent water overheating and create half-light in it.
You should provide the fish with building materials for the nest. You can put small-leaved fluctuant on the tank water surface (water lettuce), raise the water temperature to 28°C (82°F).
The male builds a ball-shaped nest using foam and plants as building materials. The nest diameter may be up to 1 meter large. During this period, the male becomes aggressive, so the female should have a shelter to hide from his attacks.
Since after the juveniles appear, the male fish starts to guard them. At that, it attacks even the female fish. She will require a lot of space to find a shelter in the tank till the juveniles grow. After building the nest, spawning usually occurs several days later.
Spawning games last about 2-3 hours. During this time, the female lays from 3 to 10 thousand eggs 2.5 – 3 mm large in the nest. After this, you should remove the female from the tank.
The eggs are lighter than water, and they float to the surface. The male gathers them and puts them in the nest. The larvae hatch in 24 hours. The fish guards its eggs and juveniles for some time after the spawning is over.
Larvae turn into juveniles 5-6 days later. They start to swim and feed on small plankton.
In the wild, the male continues guarding the offspring for 2-3 weeks more, but in captivity, you should remove him from the tank once the juveniles start to swim.
The water level should be decreased to 10 cm (4 in) and keep it like this for thirty days. During this time, the juveniles labyrinth organ is formed, and they start gasping air from the surface. In six months, they grow to be 12 – 15 cm (5-6 in) long.
In a tank you have at home, it is quite difficult or even almost impossible to obtain the juveniles due to the tank size requirements.
In theory, the breeding process is easy – the fish form a couple, build nests from bubbles where the juveniles grow, etc., but the size of the proper tank becomes a problem because it has to be a huge one.