Mastering Giant Gourami Care: Size, Diet, and Tank Maintenance

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

The giant gourami belongs to the family Osphronemidae, also known as the gourami family. This family includes various species of gouramis, which are freshwater fish commonly found in Southeast Asia. Some notable members of the Osphronemidae family include the giant gourami (Osphronemus goramy), the kissing gourami (Helostoma temminckii), the pearl gourami (Trichogaster leeri), the three-spot gourami (Trichopodus trichopterus), and the dwarf gourami (Trichogaster lalius).

They initially used to dwell in Greater Sunda Islands (Sumatra, Java, Borneo, etc.). Giant gourami has been introduced to various parts of the world outside its native range, including countries like the United States and some African nations, where it has become established in certain aquatic environments. 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.

In their natural habitat, giant gouramis are often found in areas with abundant vegetation, submerged roots, fallen branches, and other types of cover. These fish are adapted to warm tropical climates and thrive in water temperatures ranging from 75°F to 86°F (24°C to 30°C). Additionally, they prefer slightly acidic to neutral water conditions with a pH level ranging from 6.5 to 7.5.

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. Their ability to breathe atmospheric air due to their labyrinth organ allows them to survive in oxygen-depleted environments or in stagnant waters.

Description

How big do giant gouramis get?

The giant gourami (Osphronemus goramy) is known for its impressive size. It gets its full adult size at the age of about 4-5 years old. On average, adult giant gouramis can reach lengths of 18 to 28 inches (45 to 70 cm). However, in exceptional cases, they can grow even larger, sometimes exceeding 30 inches (76 cm) in length. But in aquarius, as a rule, it’s no larger than 45 cm (18 in) long. Additionally, giant gouramis have the potential to gain considerable weight, with adult specimens weighing up to 20 pounds (9 kg) or more.

How long do giant gourami live?

Giant gouramis have a relatively long lifespan compared to many other fish species. In ideal conditions and with proper care, giant gouramis can live for around 10 to 15 years in captivity. However, there have been instances where some individuals have lived even longer, reaching ages of 20 years or more. It’s important to note that individual variations can occur, and not all giant gouramis will reach their maximum lifespan. Additionally, the lifespan of giant gouramis in the wild can be influenced by various factors such as predation, habitat conditions, and availability of food resources.

How fast do giant gourami grow?

The growth rate of giant gouramis can vary depending on several factors, including genetics, diet, water quality, and environmental conditions. Generally, giant gouramis have a moderate growth rate compared to some other fish species.

During the first year of their lives, giant gouramis can experience rapid growth, and they can reach lengths of several inches within this period. However, as they mature, their growth rate slows down. On average, under optimal conditions, giant gouramis can grow around 2 to 4 inches (5 to 10 cm) per year.

This is fish with a wide and flat body. Its standard length is twice larger than its body height. They have a broad and slightly concave head.

The coloration of giant gouramis can vary depending on their age, mood, and environment. 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.

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.

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.

CharacteristicDescription
Scientific NameOsphronemus goramy
Common NameGiant gourami, kaloi fish
FamilyOsphronemidae (Gourami family)
Native HabitatSoutheast Asia, including Indonesia, Malaysia, Thailand
SizeCan grow over 2 feet (60 cm) in length
WeightUp to 20 pounds (9 kg)
LifespanAround 10-15 years in captivity
HabitatSlow-moving rivers, lakes, swamps, flooded forests
Water Temperature75°F to 86°F (24°C to 30°C)
Water pH6.5 to 7.5
DietOmnivorous; feeds on aquatic plants, insects, crustaceans, small fish
BehaviorGenerally peaceful, can exhibit territorial behavior
AdaptationsPossesses a labyrinth organ to breathe air directly
Conservation StatusNot listed as threatened or endangered
Aquarium SuitabilityRequires a large tank with plenty of space and cover

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

Tank size

The biggest problem here is tank capacity. 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).

For a single adult giant gourami, a minimum tank size of around 150 gallons (568 liters) is typically recommended. This provides enough swimming space and accommodates their size comfortably. However, larger tanks, such as 200 gallons (757 liters) or more, are even better for these fish, as it allows for more freedom of movement and helps to minimize stress.

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.

Water parameters

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. Here are the recommended water parameters for giant gouramis:

  • Giant gouramis thrive in tropical temperatures. The ideal water temperature for them ranges from 75°F to 86°F (24°C to 30°C).
  • Giant gouramis prefer slightly acidic to neutral water conditions. The recommended pH range for them is around 6.5 to 7.5. It is essential to monitor and adjust the pH level as needed, while avoiding drastic fluctuations.
  • These fish can tolerate a wide range of water hardness levels. However, a moderate hardness level is generally suitable. Aim for a general hardness (GH) level between 6 and 12 degrees dH and a carbonate hardness (KH) level between 4 and 8 degrees dH.
  • 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.

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. 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. A combination of mechanical, biological, and chemical filtration is recommended to keep the aquarium clean and clear.

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.

Tank mates

Are giant gourami aggressive?

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. In general, giant gouramis are considered to be relatively peaceful compared to some other cichlid species. They can coexist with a variety of fish in a community tank if the tank is large enough and provides adequate hiding places and territories. However, as they grow larger and mature, they may become more territorial and may show aggression towards tank mates.

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

Since giant gouramis can grow quite large, it’s necessary to select tank mates that can tolerate their size and occasional territorial behavior. As a rule, this fish is kept together with large cichlids or catfishes. Here are some potential tank mates for giant gouramis:

  • 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.
  • Consider adding bottom-dwelling species that occupy a different level in the aquarium. Suitable options may include plecos, catfish (such as Corydoras or Synodontis species), or loaches (such as clown loaches or yoyo loaches).
  • Giant gouramis can coexist with other large, peaceful community fish such as angelfish (Pterophyllum sp.), silver dollars (Metynnis sp.), large barbs (such as tinfoil barbs), and larger tetra species.
  • Some larger, peaceful cichlid species can be suitable tank mates for giant gouramis. Examples include Severum cichlids (Heros sp.), Geophagus cichlids, and certain peaceful South American cichlid species. Avoid aggressive or highly territorial cichlid species.
  • Arowanas are generally more aggressive and territorial compared to giant gouramis. While giant gouramis can exhibit territorial behavior, they are usually less aggressive. However, compatibility can vary between individual fish, and some giant gouramis may not tolerate the presence of an arowana. Aggression issues may arise, particularly if the tank is too small or lacks sufficient hiding spots and territories for both fish.

Diet

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.

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Gender differences: male vs female

There are some physical differences between male and female giant gouramis that can help differentiate them. Here are some common characteristics that can be used to distinguish between male and female giant gouramis:

  1. Size: In general, male giant gouramis tend to grow larger than females. Males can have a more robust and elongated body shape compared to females.
  2. Coloration: Male giant gouramis often exhibit more vibrant and intense coloration than females, especially during the breeding season. They may display brighter hues of gold, orange, or yellow, along with distinct patterns or markings on their bodies.
  3. Dorsal Fin: During the breeding season, male giant gouramis develop an elongated and more pointed dorsal fin compared to females. This fin may extend farther back and be more pronounced.
  4. Head Shape: Mature male giant gouramis can develop a broader and more prominent head shape than females. This difference in head shape becomes more noticeable as they grow older.
  5. Behavior: Male giant gouramis may exhibit more territorial and aggressive behavior, particularly during the breeding season when they establish and defend their territory. Females tend to be more peaceful and less aggressive.

Breeding

Giant gourami is an egg-laying fish. At the age of eight months, being 12 cm (5 in) long, they can start breeding. 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.