Glass Catfish Care, Size, Tank Mates & Diet

Glass Catfish are very good at making themselves invisible.

This ghostly looking fish looks like a creature from another planet. If you look very closely you can see their internal organs through their clear skin!

Even though they are difficult to spot you might catch just a glimpse of their glittering scales as they swim in your aquarium.

There is so much to know about the Glass Catfish before you give them a home in your tank.

Keep reading to learn everything you need to know about keeping this strange and sensational little critter…

Overview

There are several different species that are known as Glass Catfish but the Kryptopterus vitreolus is the most common. This is the fish that we will be discussing in this article.

Glass Catfish are endemic to Thailand and are also known as the Ghost Catfish or Phantom Catfish.

They are the most beginner friendly catfish and are well known for their eye catching appearance and timid personality. These catfish grow between 4-5 inches long and can live for up to 8 years.

Although they are starting to become more popular, they are still quite an uncommon find. You will almost certainly have to purchase them online and most places will label them as a Ghost Catfish.

Expect to pay around $10 for a group of 5.

However, the most difficult part about purchasing these fish is correctly identifying them!

The African Glass Catfish (Parailia pellucida) looks very similar in both appearance and size. However, P. pellucida has a black spinal cord and K. vitreolus has a translucent white one.

Juvenile Kryptopterus bicirrhis may be sold as K. vitreolus but they will turn white when they reach adulthood. Real K. vitreolus remain transparent their entire life.

Key Facts:

• Experience Required: Aquascaping and schooling fish.
• Nicknames: Ghost Catfish or Phantom Catfish.
• Color Forms: Transparent.
• Size: 4-5 inches.
• Tank Size: Minimum 30+ gallon.
• Tank Temperature: 75°F to 80°F.

Glass Catfish Care Sheet

These Catfish have a very low tolerance for changes in water quality.

Unstable water parameters also increase the risk of diseases (particularly bacterial infections and dropsy).

A fish with dropsy has a visibly distended abdomen and will be very sluggish as they try to keep up with the others in their school. Most of the time dropsy can be treated by adding marine salts to the tank but this is risky for a fish that is so sensitive to changes in salinity. You will likely need to use an antibiotic treatment.

If they are isolated from their school for any reason then they are likely very sick. They do not willingly separate from the group so you should be concerned if you see one off on their own.

When they are kept in consistent water parameters they are fairly hardy.

Also you should know that these fish must be acclimated at the same time using the bag method.

Unfortunately, it is common for this fish to have difficulty acclimating to their environment and failure is most likely if the water parameters are unstable.

Diet

Although these Catfish are omnivores they prefer to eat meaty prey over plants and vegetables.

In the wild they will eat tiny prey that they find in the water and the substrate. These include zooplankton, insects, brine shrimp and small worms.

In the aquarium, a high protein diet is the right way to go.

You can use fish flakes that are specially made for Catfish, along with frozen worms and shrimp. Your fish will also want to hunt for live prey just like they do in the wild. The best options for live prey are: water fleas and other zooplankton, brine shrimp, mosquito larvae, grindal worms and bloodworms.

These fish will not eat plants or algae on their own.

However you can encourage them to eat a balanced diet by giving them flakes or pellets which contain algae.

You can feed them:

• Daphnia
• Moina
• Brine shrimp
• Bloodworms
• Grindal worms
• Flakes
• Pellets
• Mosquito larvae
• Dried worms
• Dried shrimp

Feeding these fish is not always easy.

There are times when they will be too anxious to come out for food so you will need to feed them just outside of their hiding spot.

It is also important to make sure that there is enough food for every fish in the school. They do not eat much but still must be fed once every day. Feed them at a separate time from your other fish so that they will not be disturbed. Do not be afraid to add a little more than you think they might need.

Behavior

Glass Catfish are very elusive fish that prefer to stay out of the way as much as possible.

They will swim together in a school and even feed together.

In the wild this can confuse predators and help them to survive as swimming in a group can make small fish look much larger.

These fish are very good at turning invisible but you can see them during the quiet hours when they are unlikely to be disturbed by the other fish. You will spot them shimmering around the middle levels of the tank. They will spend a lot of time weaving in and out of plants and decorations.

The larger your school the more active your fish will be.

They will not interact with other fish outside of their school.

Habitat and Aquarium Set Up

In the wild these Catfish live in areas that they can blend into.

They are often found in slightly turbid waters with enough light to let plants grow.

In areas with a lot of leaf litter, a predator may mistake them for leaves or debris floating in the water. Underwater vegetation grows densely in these areas which provides a place to hide when things get scary.

They inhabit the mid-river areas where there is enough space for their whole schools. These areas experience moderate currents and flooding during the rainy season.

To keep these fish you will need a 30 gallon tank.

This will be large enough for a school of 5 (which is the minimum acceptable group size). You should add 5 gallons for each new addition to the school.

The most important part of keeping these fish is maintaining stable water parameters.

Do not allow your temperature, salinity, or pH to rise or fall.

You should keep the water temperature between 75-80°F, ph 6.5-8.0 and water hardness 8-10 dGH.

For substrate you can use soft sand or mud that is enriched with leaf litter and other organic debris.

A moderate current is needed to simulate the fish’s natural environment and this can be achieved by using an external filter. External filters are also quieter and less distressing for them.

When picking out your aquarium lights you should pick an intensity between 3 and 5 watts per gallon.

For decorations you can scatter pinecones, twigs and wet leaves around your tank to match your fish’s natural environment. Plants are the most important decorations and you will want to include a lot of them in this setup. Use middle, background and edge plants to keep the foreground open for schooling.

Glass Catfish Appearance

It is important to know exactly what K. vitreolus look like, so you can make sure you are not purchasing a different species.

Glass Catfish will range from 4-5 inches once fully grown.

Their body is long and slender and looks like a leaf. It is completely transparent but it does shimmer when the light hits it.

When you take a close look at this remarkable little fish you can see their bones and all of their internal organs. All of their internal organs are clustered near their head. You can see the brain, heart, stomach, liver and kidneys.

They do not have scales but you can see the thin outlines of every bone in their body. Their visible spinal cord is white and travels from their head all the way to their tail. The intestine is parallel to the spinal cord, on the ventral side.

Catfish have very small head and a pointed snout. Long, filamentous barbels on their snout help them detect water pressure and even magnetic activity.

They only have 4 fins – a very tiny pair of clear pectoral fins, a V-shaped caudal fin, and a long anal fin that travels down the length of their body.

Varieties

While it may appear they change colors in certain lights, they do not.

These fish only come in transparent.

There are many copycat species that are often misidentified so we have provided a description of some of the most common:

• Kryptopterus minor: This species is identical to K. vitreolus except for their size. K. minor only grows up to 3 inches and has a slightly rounded snout.
• Kryptopterus bicirrhis: The Indian Glass Catfish is slightly larger than K. vitreolus, and is only transparent as a juvenile. It grows up to 6 inches long and turns white or grey when they reach adulthood.
• Parailia pellucida: The African Glass Catfish grows up to 6 inches in size and has a black spinal cord instead of a white one.

Tank Mates

These are schooling fish so they must be kept together.

You can keep them with a school of at least 5, but it is better to aim for a group of 7-12.

Never keep these fish in a group of less than 5. A small group size leaves them vulnerable to anxiety and shock which can lead to death.

These fish are very docile and do not interact with other fish outside of their schools.

Because of this they can get along well in freshwater communities.

In the wild they can be found with Harlequin Rasboras, Kuhli Loaches and other Thailand natives. Fortunately, many of these are available for the aquarium too.

The following fish make great tank mates:

• Harlequin Rasboras
• Kuhli Loaches
• Bettas
• Zebra Danios
• Celestial Pearl Danios
• Dwarf and Pearl Gouramis
• Cory Catfish
• Mollies
• Platys
• Swordtails
• Mystery Snails
• Rabbit Snails
• Bamboo Shrimp

However you should be careful with small invertebrates.

These fish are likely to try and eat them.

You should also watch out for small minnows like Chili Rasboras and small Tetras.

Tiger Barbs and other rambunctious Barbs should be kept away. Their boisterous antics are likely to frighten these peaceful Catfish.

There is no real safe Cichlid species to keep either.

While some will recommend the Angelfish or Kribensis, it is better to leave all Cichlids out of this setup.

Breeding Glass Catfish

Unfortunately Glass Catfish have only been bred in home aquariums a few times.

Most of these successful attempts have been achieved by hormone injections and artificial fertilization.

It is very difficult to do.

Their reproductive habits in the wild are not well researched but we do know that they breed during the wettest part of the year.

You can simulate flooding in your tank by adding small amounts of dechlorinated water and gradually lowering the water temperature from 77-74°F. You should include aquarium plants in your breeding tanks such as Java Ferns and Hornwort.

When getting your fish into breeding condition you should feed them live prey up to 3 times a day.

Males and females will rub their barbels together when they are about to pair off. After this the female scatters tiny clusters of eggs under your aquarium plants.

The eggs take up to 4 days to hatch and the hatchlings will emerge ready to eat small live prey. Unlike most larval fish they do not have a yolk sac after hatching. You should fill your tank with brine shrimp for the fry to eat. As they grow larger you can feed them insect larvae and microworms.

It is unknown exactly how long it takes these fish to reach maturity.

But you can add them to your community tank when they reach around 3 inches in size.

History and First Sighting

The Glass Catfish has a rather confusing history.

This is because there are several similar species that share the same name and family (Siluridae).

Way back in 1934 mature K. vitreolus were often confused with juvenille K. bicirrhis.

They were believed to be the same fish and were introduced to hobbyist at the same time.

As the species gained popularity some hobbyist began to notice that some of their Catfish turned opaque as they got older, and others did not.

It was not until 2013 when ichthyologist Maurice Kottelat found the answer.

The transparent adult Catfish were recognized as an entirely different species and an identification key was drawn up in order to tell the two species apart.

After their official classification in 2013, K. vitreolus became the most common Glass Catfish species in freshwater aquariums.

Frequently Asked Questions

How big do glass catfish get?

Glass Catfish will grow up to 5 inches in size.

Can glass catfish live alone?

A single Glass Catfish cannot survive for very long.

These fish are simply not meant to live on their own and need to be kept in groups of at least 5.

When kept alone they are extremely anxious and the stress could eventually kill them.

Are glass catfish actually catfish?

Glass Catfish are true Catfish although they may not look like regular Catfish.

They belong to the order Siluriformes which includes all freshwater and saltwater Catfish.

Why is my glass catfish turning white?

Glass Catfish turn white when they are sick.

You should isolate them until the cause is determined. White spots or lesions over their body can indicate ich or a fungal disease. If this happens then you should immediately quarantine and medicate the affected fish.

Summary

A school of Glass Catfish offer a unique opportunity to observe some fascinating group dynamics.

If you keep them in a group of 5 or more and build a safe environment then these fish will get along just fine in your freshwater aquarium.

They are almost otherworldly in their appearance and nothing like anything you have ever seen before.

Do your Glass Catfish show themselves often?

Let us know in the comments section below…