The glass catfish (Kryptopterus vitreolus), also known as the ghost catfish, or the phantom catfish, is a unique species of small catfish native to Asia. As the name implies, these catfish have a body that is transparent, with their skeletons and internal organs clearly visible. The only time their body will become translucent – turning a milky white color – is during serious illness or when near to death.
The Kryptopterus vitreolus available in the aquarium trade were long thought to be Kryptopterus bicirrhis, but were then later classified as Kryptopterus minor, before finally being identified as Kryptopterus vitreolous in 2013. Both other catfish are only rarely seen in the aquarium trade, with K. minor being especially rare.
|Care Level:||Moderately Difficult|
|Life Span:||8 Years|
|Size:||3 inches (8 centimeters)|
|Minimum Tank Size:||30 gallons (110 liters)|
The glass catfish inhabits a narrow area of coastal drainages in Thailand, living primarily in streams and rivers. It can be found in slow-moving and standing water, with many being found in brown water, or acidic black water areas. However, it can also be found in free-flowing, non-blackwater habitats.
A mature aquarium is recommended for glass catfish, as they are often very sensitive to even minor changes in water conditions. They should only be added to a fully cycled and heavily planted aquarium, otherwise, the fish may become ill.
Glass catfish are known to form tight schools and should always be kept in groups of six or more. While glass catfish are generally peaceful, they have been known to prey on fish fry and eggs.
While many people recommend glass catfish for community tanks, it can prove difficult to find tank mates who won’t bully them. Even the most peaceful fish will often overwhelm glass catfish with their behavior, sending them into near-permanent hiding.
Glass catfish should be kept in a dimly lit aquarium, with plenty of tall and floating plants to help filter the light. Tall plants also help these fish to feel more comfortable, and they will spend more time out in the open when provided with sufficient plant shelter. It’s not unusual to see an entire school of glass catfish hiding under a leafy plant together.
The aquarium substrate should be a muted color, and a layer of dried leaves along the bottom can be provided to help mimic their natural environment. The tannins that leach from dried leaves have been shown to be beneficial to fish from blackwater environments. However, some leaves can be dangerous for fish, so always identify the leaves before adding any to an aquarium.
A strong filter is a requirement for a glass catfish aquarium, and it’s recommended to strongly over-filter their water. As they require such strong filtration, it’s usually best to use a canister filter. We strongly recommend the Fluval Canister filter, which is a reliable and excellent filter and helps to keep the aquarium water sparkling clean.
Glass catfish are believed to feed on small invertebrates and larvae in their natural environment. However, they haven’t been adequately studied to state that with certainty at this moment.
However, these fish’s mystery diet isn’t a problem, as most will accept dried fish food in the aquarium. One of the best foods you can offer them is Hikari Micro Pellets. This food provides essential nutrients and is ideal for smaller aquarium fish like the glass catfish.
If a glass catfish won’t accept dried fish food, they should be offered live and frozen food instead. Frozen brine shrimp, bloodworms, daphnia, and cyclops will all be greedily accepted. Some good live food options to offer them are live mosquito larvae (illegal to culture in some areas), daphnia, blackworms, and gutted loaded brine shrimp.
Over time, any fish who won’t accept dried fish food can be transitioned from the live and frozen foods to store-bought foods. A good strategy is to mix the dried food in with the frozen food and then slowly reduce the amount of frozen food over time. Eventually, the fish should be eating dried foods without any difficulties.
The information regarding glass catfish breeding is inconsistent at best. While a report from 2013 stated that no glass catfish were being bred in captivity and all the fish available in the aquarium trade were wild-caught, a more recent report from 2019 claimed the majority of the fish for sale were being bred in Asian fish farms.
However, while it may be true that they are being bred on fish farms, there is no reliable information or recorded instances of these fish being bred in captivity.
Tank Mates for Glass Catfish
While several species of fish can be kept with glass catfish – especially fish who inhabit similar water habitats– it’s usually best to keep glass catfish in a species only tank.
But if someone is determined to keep these fish in a community tank, there are a few fish that should make good tank mates. These include neon tetras, cardinal tetras, and harlequin rasboras. Larger fish should be avoided as they tend to out-compete and threaten glass catfish.