Glass catfish are named so because they look like they’re made of glass. These fish are see-through! Their clear bodies allow you to view their bones and organs. This unique feature makes them popular aquarium pets.
What Are Glass Catfish?
Glass catfish — also called ghost catfish, transparent catfish, or phantom catfish — are a group of species in the catfish genus kryptopterus. While this genus has multiple species, only three of the species found so far have clear bodies that qualify them to be called glass catfish:
- Kryptopterus minor
- Kryptopterus piperatus
- Kryptopterus vitreolus
For a long time, especially in the pet trade, a species called Kryptopterus bicirrhis was often mistaken for Kryptopterus vitreolus.
The key difference between these species is that while the body of K. vitreolus is completely clear, only the area near the head of K. bicirrhis is clear. It’s likely that most glass catfish in the aquarium trade that were once labeled K. bicirrhis are or were actually K. vitreolus.
The clear appearance of K. vitreolus and the other glass catfish is what makes them so fascinating. Their bodies are completely see-through. This allows you to see their organs, bunched up by their heads, and their spines. You can even see their heart beating with a magnifying glass.
Why Are Glass Catfish Clear?
No catfish, including those of the genus kryptopterus, have scales. But what makes glass catfish transparent is their lack of pigmentation.
Unlike other types of catfish, their skin cells don’t carry color. They’re completely clear. It’s not known exactly why this is, but when glass catfish die, they become a milky white color, indicating that maybe something the catfish does while alive produces the cells.
Like most other species of catfish, glass catfish have barbels, the “whiskers” on their heads that give the catfish their name. These barbels are used as feelers to find food. In glass catfish, they are completely clear like the rest of the body.
The fins of the glass catfish are also see-through. Glass catfish have an anal fin, or a fin that runs along the underside of their body. This fin runs from their head to their dorsal fin, or tail fin, which is forked. Another feature that sets glass catfish apart from other types of catfish is their lack of a dorsal fin, a fin that runs along the top of the fish. In fact, this is where the genus name comes from. Kryptopterus is Greek, with the root ‘kryptos’ meaning hidden and ‘pterus’ meaning fin. Kryptopterus means “hidden fin.”
What Size Are Glass Catfish?
Glass catfish size can vary widely between species. Kryptopterus vitreolus usually grows to about 3.1 inches (8 centimeters), while Kryptopterus minor reaches about 2.7 inches (6.8 centimeters) on average. Kryptopterus bicirrhis, the fish that K. vitreolus was often mistaken for, can grow much larger, an average of 5.9 inches (15 centimeters).
It’s almost impossible to tell male and female glass catfish apart. The only difference is that males are usually slightly smaller than females.
Glass Catfish Habitat
All species in the genus kryptopterusare found in freshwater habitats in Southeast Asia. The exact location depends on the species.
- Kryptopterus minor is found mainly in Indonesia.
- Kryptopterus piperatus is typically found within forest rivers with a moderate current in Indonesia, especially the Alas River and Lembang River.
- Kryptopterus vitreolus is found throughout the peninsular and southeastern areas of Thailand, usually in slow-moving or standing murky water. There have been reports of sightings in Malaysia, but those are yet to be verified.
While many species of catfish are bottom feeders that keep to the river floor, glass catfish often prefer to swim in the middle of the water. This is another reason they’re a popular aquarium fish, as they’re much more active than other species of catfish.
Glass catfish tank size
Experts recommend keeping glass catfish in groups of six or more. So you’ll need an aquarium that can hold at least 30 gallons. This should be enough for about eight fish. Add 2 gallons for each additional fish.
Glass catfish seem to do best in environments similar to their natural habitat. Create a calm tank with tannin-stained water, lots of live plants, branches, and other décor. Subdued lighting and slow water flow also help. You can also go the extra mile and create a biotope tank by adding plants native to Southeast Asia.
Glass Catfish Diet
In the wild, glass catfish mostly eat very small fish or small invertebrates such as:
- Mosquito larvae
- Tiny crustaceans, such as water fleas (genus Daphnia)
- Zooplankton
Glass Catfish Lifespan and Life Cycle
On average, glass catfish live for about six to eight years.
There isn’t much information known about the life cycle or breeding practices of glass catfish. Glass catfish are very difficult to breed in captivity.
How big do glass catfish get?
Glass catfish grow to a maximum size of 3 inches. That measurement doesn’t include the long, thin sensory barbels on their faces.
Glass Catfish Care
Thanks to their unique look, glass catfish, especially K. vitreolus, are a popular freshwater aquarium fish. They’re also relatively easy to look after — as long as you give them what they need.
Tankmates. Glass catfish normally travel in groups, called schools. As a result, they need to be around other fish. They should be in schools of six or more.
Glass catfish are generally peaceful fish. If you’re keeping them in a tank with other fish, they need to be with species that are peaceful and not too large.
Tank and water. For a group of five or so, glass catfish should be in a tank that’s at least 30 gallons. The more fish you have, the larger the tank needs to be. Their tanks should have both open areas and hiding spots. Some of the best things to keep within their tank are plants that create cover, rocks, and other ornaments.
While glass catfish aren’t difficult to care for, they do require certain water parameters. This includes:
- Hardness level between 8 and 12 degrees of general hardness (dGH)
- pH between 6.5 and 7.5
- Temperatures between 75 F and 80 F (24 C and 26.7 C), although they can survive in temperatures between 72 F and 82 F (22.2 C and 27.8 C)
The water in the tank should have a medium flow to it.
Diet. In the wild, glass catfish mostly eat very small fish or small invertebrates. When keeping pets in an aquarium, you should try to imitate their wild diet as closely as possible. Daily pellet or flake food is important and will provide the basic nutrients for your fish. For added protein, you can also offer your glass catfish:
- Bloodworms
- Brine shrimp
- Grindal worms
- Tiny crustaceans such as daphnia
- Zooplankton such as moina
Glass catfish are low-maintenance fish aside from their narrow water parameters. They’re also fascinating to look at and can be an excellent addition to a freshwater aquarium.
Takeaways
Glass catfish are small, see-through fish native to Southeast Asia. They are peaceful and fairly low-maintenance fish that live for about six to eight years. In the wild, they survive on mosquito larvae, tiny crustaceans, and zooplankton. When keeping them in an aquarium, try to feed them the same food they eat in the wild. Daily pellet or flake food offers basic nutrients. You can also feed them bloodworms, brine shrimp, and grindal worms.
Glass Catfish FAQs
Are glass catfish friendly?
Glass catfish are known for their peaceful demeanor.
Can fish see color in water?
Yes. Catfish have cones in their eyes, which are needed for color vision.
Do catfish have good eyesight?
Yes. They are particularly sensitive to shadows.
