A Beginner’s Guide to Keeping Glass Catfish: Care, Size, and More

Glass catfish (lat. Kryptopterus spp.) — is a kind of freshwater ray-finned fishes of catfish family that inhabit in South-Eastern Asia. These fascinating fish are popular among aquarium enthusiasts due to their unique appearance. The glass catfish is named for its transparent appearance, which allows you to see its internal organs, including its skeleton and digestive tract. The first thing that catches the eye when you see this fish is how transparent it is – you can clearly see its visceral and spine.

Habitat in the wild

The glass catfish, scientifically known as Kryptopterus spp., belongs to the family Siluridae. The Siluridae family is a group of catfish commonly referred to as “sheatfish” or “sheatfish catfish.” They are predominantly freshwater fish found in Southeast Asia, including countries like Thailand, Indonesia, and Malaysia.

Glass catfish are native to Southeast Asia and are primarily found in freshwater habitats in countries such as Thailand, Malaysia, Indonesia, and Cambodia. They inhabit slow-moving rivers, streams, and flooded areas with dense vegetation. Glass catfish prefer areas with abundant hiding spots such as submerged tree roots, aquatic plants, and driftwood.

These fish are known to be found in blackwater habitats, where the water is stained brown due to the presence of tannins released by decaying organic matter. They are typically found in the lower to middle levels of the water column, often in groups or shoals. In the wild, glass catfish are sensitive to changes in water quality, especially temperature and pH, and they require stable and well-maintained aquatic environments to thrive.


How big do glass catfish get?

Glass catfish typically grow to a size of about 4-5 inches (10-12 centimeters) in length. However, it’s important to note that this size can vary slightly depending on the specific species within the Kryptopterus genus. Some species may reach slightly larger sizes, while others may remain slightly smaller. As with any fish, factors such as genetics, diet, and environmental conditions can also influence the growth and size of individual glass catfish.

How long do glass catfish live?

In captivity, glass catfish typically have a lifespan of around 3-5 years. However, it’s important to note that the lifespan of glass catfish can vary depending on various factors, including the quality of care, diet, water conditions, and genetics.

The most striking feature of glass catfish is their transparent or translucent body. There are no pigments in the body, this catfish is transparent to the bone – you can see its skeleton and costal bones. It gives them a ghost-like appearance.

Glass catfish do not have scales covering their body, which contributes to their transparent appearance. Instead, their skin is smooth and transparent. In the wild, in glass catfish habitat such a body structure helps these harmless fish to hide from predators. Catfish just disappears in the muddy water in the wild. The number of melanophores (cells that contain pigment in them) is quite low, so the muscles are transparent and light colored. There’s one more pigment in the body except melanophore: it’s guanine that is responsible for metallic coloring.

This pigment develops inside the cells in form of crystal plates that act like a mirror, reflecting light and color of the environment and this way it makes the fish masked in water.

The glass catfish has a couple of long barbels on its upper lip. These whisker-like structures help them detect food and navigate their surroundings.

Even though it may seem that the fish doesn’t have a dorsal fin, if you look closer, you can see a small fin right behind the head. They possess a long anal fin on the underside of the body. Their tail fin is forked, which means it splits into two lobes. This type of tail fin aids in their swimming ability.

Scientific NameKryptopterus spp.
Common NamesGlass catfish, ghost catfish, phantom catfish
Native RegionSoutheast Asia
HabitatFreshwater rivers, streams, and flooded areas with vegetation
AppearanceTransparent body with visible internal organs and skeletal structure
SizeTypically grows up to 4-5 inches (10-12 centimeters) in length
BehaviorShoaling species that prefers to be in groups
DietOmnivorous, feeding on small crustaceans, insects, worms, and plant matter
Water ConditionsPrefers soft, acidic water with temperatures between 75-82°F (24-28°C)
Aquarium SuitabilityRequires a well-maintained aquarium with plenty of hiding spots and plants
LifespanTypically lives for 3-5 years in captivity
Special ConsiderationsSensitive to water quality changes, requires regular water changes

Difficulties in keeping

So, it becomes quite clear why this fish is called a glass one. Glass catfish are rather sensitive to their tank water parameters change and it should be put only into a settled tank with low nitrates level. Besides, the fish is rather timid and sensitive one, so it should be kept only in a school and with some peaceful tank mates.

Care is rather difficult since the fish is quite a demanding one, that can be recommended only to experienced aquarists. The fish hardly stands changes of tank water parameters, it is timid and prone to different diseases.

Care and keeping in a tank

Tank size

When it comes to tank size for glass catfish, it’s important to consider their natural behavior and space requirements. Ideally, you should provide a tank that is at least 20 gallons (75 liters) in size for a small group of glass catfish. However, larger tanks are always better for fish in general, as they provide more swimming space and stability in water parameters. If you plan on keeping a larger shoal of glass catfish, you will need to increase the tank size accordingly.

Tank decor

In the tank it’s desirable to simulate the glass catfish natural environment (which is streams and rivers with flowing water). To achieve this use lots of live plants, however there should be some space for the fish to swim and some water flow running along the tank length.

Adding some floating plants will make the fish fill safe and also they’ll create in the tank some shaded spots, which the fish likes some much in the wild.

After being put into their new dwelling the freshwater glass catfish may lay on the bottom of a tank. Don’t panic! They are just a bit stressed. As soon as they get acquainted with their new home, they’ll get up from the tank bottom and start swimming. You may sufficiently lessen the level of stress after removal into a new tank by putting the fish into the unlit tank.

Water parameters

Glass catfish prefer a relatively warm aquarium with a temperature range between 75°F (24°C) and 82°F (28°C). To keep the fish healthy the tank water temperature shouldn’t be less than 24 °C and there shouldn’t be any abrupt water temperature changes.

The ideal pH level for glass catfish is slightly acidic to neutral. Aim for a pH range between 6.5 and 7.5. It’s important to avoid extreme fluctuations in pH as it can stress the fish.

Glass catfish prefer moderately soft to moderately hard water. Aim for a water hardness level between 5 to 12 dGH (degrees General Hardness).

Also you should control the level of ammonia and nitrates in it, since this catfish is rather sensitive to these parameters. Here are some points that should be kept in mind when putting your ghost catfish into a tank for the first time. Nitrate levels should be kept below 20-30 ppm (parts per million) through regular water changes.

This species is very sensitive to the water purity, so the water filtration must be very efficient and the tank water should be renewed regularly. Glass catfish don’t like bright light, therefore they are active in the shaded parts of the tank.


In the wild, they primarily feed on small invertebrates, insects, larvae, and zooplankton. When kept in aquariums, their diet should mimic their natural feeding habits as closely as possible. Here are some guidelines for feeding glass catfish:

  • Glass catfish prefer eating blood worm, tubifex, white worms, brine shrimp. These options mimic their natural prey and offer essential nutrients.
  • Glass catfish readily accept high-quality commercial fish pellets or flakes formulated for omnivorous fish. Also the fish may adjust to some small sized granules slowly going down in the water. Keep in mind that the feed should be small, because the fish has a small mouth. Though glass catfish may also feed on some juveniles, since they do it in the wild.

Feed glass catfish small amounts of food two to three times a day. They have small mouths and stomachs, so it’s crucial not to overfeed them. Feed only what they can consume within a few minutes to avoid excess food sinking to the bottom and fouling the water.

Tank mates

How many glass catfish should be kept together?

Is a peaceful and even timid fish. Glass catfish are social fish that prefer to be kept in groups or shoals. To ensure their well-being and reduce stress, it is recommended to keep them in groups of at least six individuals or more. A larger group will provide a more natural and comfortable social dynamic for them. The presence of companions can help reduce stress, promote natural behavior, and encourage better overall health. Glass catfish feel themselves much better and confident in a group of fish, they swim freely in the middle water layer and in the middle of the tank.

Glass catfish are generally peaceful and can be kept with a variety of tank mates. They feel more comfortable in the company of some calm fish of their size. Here are some suitable tank mates for glass catfish:

Gender differences: male vs female

Distinguishing between male and female glass catfish can be challenging, as they exhibit minimal external sexual dimorphism. Unlike some other fish species, glass catfish do not possess prominent differences in size, coloration, or fin shape between males and females.

Due to these physical similarities, determining the sex of a glass catfish without resorting to internal examination or breeding behavior can be quite difficult for most aquarium hobbyists. To accurately identify the gender, one would need to observe breeding behavior, which includes the formation of pairs and the female’s abdomen appearing rounder when carrying eggs.

In general, for most casual aquarium setups, differentiating between male and female glass catfish may not be necessary or easily achievable without further assistance or expert knowledge.


There’s very few information about glass catfish breeding. Breeding in a tank is a very rare event, however there’s some success in it in some far east farms. In the wild the breeding process is a seasonal one, so when simulating the rain season in a tank one may provoke female to breed.

To do this you have to decrease the water temperature up to 22-24°C and decrease the tank water level up to its half and then each day add soft (5-10%) water with some small portions.

To stimulate the breeding it’s desirable to feed the glass catfish with large amount of live feed. Then the female scatter about several hundreds of eggs on the tank plants. After the breeding is over you should remove fish-parents from the tank. Simulation of the rain season will help the eggs to grow. Start feed for the juveniles is encapsulated brine shrimp.