Glass Catfish – A Complete Guide (Care, Diet, Facts)

Beautiful, haunting, and mysterious, the Glass Catfish can add an element of intrigue to any aquarium.  These evocative fish have captured the fascination of hobbyists since their discovery.  Also known as Ghost Catfish or Phantom Catfish, these creatures will earn the admiration of both seasoned and new aquarium owners.

Their transparent skin reveals the inner make-up of the fish.  At times these fish seem to disappear inside of the tank.  Moments later they will materialize in a different location heading in a new direction.  They seem able to dart in and out of existence.

Once, found only in the jungle rivers of Thailand, the Glass Catfish can now grace your aquarium.  Much like the glass they are named for, they can require delicate handling and care.  A thoughtful aquarium owner can master this care and keep these phantoms healthy.


Glass Catfish Basics

The Glass Catfish was initially misidentified as a more aggressive separate species.  Until 2013, these fish were confused with ones that weren’t typically kept as pets.

This confusion is likely a result of just how isolated their natural habitats are.  They are also difficult to study because of how hard it is to breed them in captivity.

The Kryptopterus bicirrhis species may be in your house right now!  Don’t expect to find it in your aquarium though.  This species of Glass Cat is often used in the making of fish sauce.  Fish sauce is made from fermenting fish and adding salt.

The species you’ll want in your tank is the Kryptopterus vitreolus.  Other “Glass Catfish” are actually Kryptopterus bicirrhis or K. minor.  Unravelling the scientific name reveals that Krypto is Greek for “hidden” or “secret”.  This makes perfect sense based on their appearance.

They have two long barbels at the front of their face.  Barbels, also known as barbs, are fleshy knobs near a fish’s mouth.  They can sometimes look like whiskers.

Scientists from Michigan State University are studying these barbels.  Specific to the Glass Cat’s barbels is the ability to detect electromagnetic waves.  They believe there is a connection between this feature and curing diseases in humans like Parkinson’s Disease.

Glass Cats are a freshwater catfish.  Unlike most catfish, the Glass Cats live in the mid to upper levels of a body of water.  Instead of living solitary lives in the mud, they developed into social creatures moving in and out of the light.

While keeping your Glass Cats healthy may be challenging, they can provide companionship for up to eight years in your tank.

Because Glass Cats are known to be difficult to keep healthy, novice aquarists should proceed with care.  A thorough understanding of basic aquarium upkeep is necessary to maintain a Glass Cat school.

Glass Catfish Behavior

Known for their peaceful nature, Glass Cats enjoy being part of schools of around five to twelve.  Larger schools are very common in the wild.

Convincing several lone Glass Cats to form into a school may take some time.  Glass Cats are very timid when put in a new environment.  Don’t be concerned unless this behavior lasts for more than a couple weeks.

After they get familiar, expect these lone rangers to start forming a school.  They don’t enjoy solitude and will probably stop eating if left alone too long.

Once the school is formed, they will begin travelling together around their home.  They will also feed and rest together, all while facing the same direction.

Glass Cats remain active during the day.  This doesn’t mean they like bright light, though.  At night you may see a cool formation appear.  They will all face one way and float in place while moving just enough to stay the same speed as the water current.

During this activity you may notice they will point their noses up at a 45-degree angle while their tails face down.  They will only do this when in larger schools.

You may notice the Glass Cats hiding.  They will congregate under plants or rocks with overhangs when nervous.  They are a very timid fish.

Look at what could be causing this.  This behavior shouldn’t occur all the time.  This is a sign of stress and could eventually lead to bigger problems.

Appearance (Or Disappearance?)

These fish are almost completely clear.  They have very little pigment in their body.  These pigment containing cells are called melanophores.  This makes their muscles and blood virtually invisible.

When viewed in the right light they can display a metallic pearly gleam.  This is the result of a pigment called quanine.  This pigment forms layers of crystals on the fish’s skin.

Like all catfish, they lack scales.  This makes their bones clearly visible through the skin.  Only through close examination can you see the ribs and spinal column.  Even harder to identify is the dorsal fin located on the back.

In certain conditions it may be impossible to see the fins at all.  They are so small and transparent, only the closest inspection will reveal them.  This can give the effect of them remaining perfectly motionless.

All the organs are located at the head of the fish.  They are contained within a visible silver sack behind the eyes.

Glass Cats don’t have sexual dimorphism.  This means there is no noticeable difference between the male and female fish.  Until the female begins developing eggs inside the belly, it is nearly impossible to tell them apart.

Expect an average size of about four inches.  If your Glass Cats are really thriving, they may grow up to six inches.


Natural Requirements

In the wild, Glass Cats can be found in the rivers and streams of Thailand and surrounding areas.  They will stay towards the middle of the water column finding slow moving water where they can capture food.

As you can imagine, their appearance helps keep them safe in the natural environment.  They will hide beneath or behind plants and rocks when threatened.

A Glass Cat’s barbels help them sense the environment around them.  This becomes very important when they venture to the bottom of murky riverbeds.

They mate during the rainy season when water temperature drops.  Their eggs are laid on various vegetation.

Aquarium Requirements

As mentioned above, Glass Cats can be rather fragile.  They won’t handle temperature changes very well.  Any type of chemical or PH change in the water can spell disaster.

Coming from tropical origins, Glass Cats will flourish in water temperatures between 75 and 80 degrees Fahrenheit.  Water hardness should stay between KH 8-12.  Acidity should be PH 6.5 to 7.  The water should have a mild flow.

Replicate their natural hiding spots by adding plants to the tank.  These plants will also help clean the water without having to add excessive cleaning agents.  Choose plants that float and have broad leaves.  This will provide hiding spots for the fish and a surface for fish eggs.

Due to the Glass Cat’s delicate skin and fragile barbels, sand and tiny gravel should line the bottom of the tank.  Larger rocks with sharp edges should be avoided.

Avoid bright lighting in the tank.  This will stress the school and discourage travel around the aquarium.  A soft light should be fixed to the top of the tank, mimicking the natural environment.

A filter is a must have for Glass Cat’s.  They are susceptible to bacteria and toxins that can build up in the tank.  A good filter will help maintain low bacteria levels and provide a small current.

Finally, look to provide one gallon of water per Glass Cat.  This requires a 35 to 40-gallon tank for a small school of the fish.  Less room will limit the number of spaces the fish can go when it’s scared.  This will ultimately lead to stressed and sick fish.

Fish Tank Neighbors

Bad Neighbors

For a fish, a bad neighbor means you get invited to dinner because you’re the main course.  Aggressive fish are a no-go for your Glass Cats.  Avoid bully species to prevent shattering your Glass Cats.  These include:

  • Oscars- Glass Cats are too small and passive to interact with this big beast. Oscars live better with fish of similar size.
  • Cichlids- Cichlids establish feeding territories and will defend them by chasing and killing other fish. The Glass Cats can’t compete with this behavior.
  • Freshwater Sharks- These guys aren’t actually sharks, but rather a type of catfish. Despite the family relations, they are territorial and may attack the Glass Cats.
  • Tiger Barb- Tiger Barb prefer similar school sizes. They grow to about three inches.  Considered semi-aggressive, Tiger Barb could cause trouble for the Glass Cats.  It’s possible that if your Glass Cats are fully grown, they can hold their own.  It is a risk, though.

Good Neighbors

Some species seem custom made to move in next door with Glass Cats.  These species will exhibit passive behavior.  They are typically schooling fish of around the same size.

  • Mollies- Mollies can throw a punch but generally only in self-defense. They will mostly mind their business with Glass Cats.
  • Neon Tetra- Neon Tetras are happy to swim around with each other and look pretty. They can create a nice contrast in the same tank with Glass Cats.
  • Dwarf Gourami- A Dwarf Gourami’s worst enemy is another Dwarf Gourami. There can be only one!  If they are by themselves, they should make good neighbors.
  • Cory Catfish- These guys are like having your cool cousins over. They are very social, even to other fish, though they can also thrive without other Cory Catfish.

Regardless of the reputation of a fish, always use caution when adding a new one to your aquarium.  Individual fish can have personalities of their own.

Consider quarantining new fish from two to four weeks in order to identify any untreated illness or lice.  It is a real shame to invest time and effort in your tank only to infect it with a newcomer.

Glass Catfish Food

Glass Cats will eat several different types of food.  This includes plants and meat, making them omnivorous fish.  In the wild they will have a varied diet of mosquito larvae, bloodworms, shrimp, and juvenile fish.

Not interested in breeding your own mosquito larvae?  There are simpler options.  Freeze dried blood worms are available for purchase.

Eventually, it is possible to wean the Glass Cats from the other items and get them eating flake type food.  They will even eat small pieces of vegetables.

Given their timid nature, feeding time for your tank must be carefully planned.  The Glass Cats aren’t going to compete with other fish to get their fill.  If this goes on for too long the Glass Cats will actually become skin and bones!

Try dropping food in one side of the tank to encourage the more aggressive fish to move to it.  While those are feeding, drop more food in the vicinity of the Glass Cats.  Provide enough food for the Glass Cats to feed for about two minutes.

Glass Catfish Care

These fish get sick easily.  If your tank is properly maintained than most of these problems can be avoided.

Be aware of overfeeding and stress.  Overfeeding will cause polluted water that can lead to other issues.  Fish under stress for a long enough period will develop other illness.

If you notice your transparent fish getting less transparent, pay attention.  Very ill Glass Cats will begin turning white.  This usually means the fish is near death.  A dead Glass Cat will also turn white.

Keep in mind that this is not necessarily a sign of a specific illness.  It is an indication of the overall health of the fish.

Common afflictions to watch out for include:

  • Lice- These guys can be introduced to your aquarium through un-quarantined fish and contaminated plants. They will latch onto your fish and lay eggs.  You will need to treat the entire tank and remove the lice from the fish.
  • Fungal Infection- It’s usually identifiable as a white cottony substance. This color can change to a gray or red if left unchecked.  It starts as spore found in the water.  A lot of decomposing material in the tank can encourage the fungus.  Freshwater salt treatments or antifungal additives can stop an outbreak.
  • Ich- Ich is a single-cell parasite that will damage the tissue of a fish and eventually lead to death. It will look like white spots on a fish.  It is commonly treated by increasing the water temperature and adding salt.  Chemical solutions can also be added.
  • Dropsy- This is recognizable as swollen stomachs in your fish. This is caused by bacterial infections within the fish.  Isolate affected fish as soon as possible to avoid losing all your fish.  Treat with antibiotics and high-quality food.  A salt treatment may help kill bacteria as well.
  • Fin Rot- Another bacterial infection, fin rot can manifest as ragged fins on your fish. Water quality must be improved to get rid of the bacteria.  Regular tank maintenance can prevent it from coming back.

Breeding Glass Catfish

In the wild, Glass Cats begin breeding during periods of heavy rain.  This heavy rain lowers the temperature of the water.  The females lay eggs on plant leaves.  After a few days these eggs will begin hatching.

There has been little success in breeding Glass Cats in captivity.  Your best chance is to replicate the naturally occurring conditions within your aquariums.

In order to do this, begin lowering the temperature of the water until it reaches 73 degrees Fahrenheit.  Add small amounts of fresh water each day to represent fresh rain fall.

Increase the amount of live food you give them.  This is believed to help the fish breed by giving them enough extra energy to encourage spawning.

Once eggs have been laid, the parents should be separated from them.  This can be done by moving the adults to a new tank or the eggs to a bowl.

The eggs should hatch within a few days.  The baby fish can be fed brine shrimp to get them growing rapidly.  Once they are big enough to eat the brine shrimp they can be reunited with their parents.


Glass Catfish will challenge the abilities of aquarium owners.  The reward for this mastery is a beautiful school of fish that will make your tank stand out from others.

They can bring a unique look to your fish habitat.  Their distinctive characteristics help illustrate the vastness that Mother Nature has given her creatures.  If you can establish a good maintenance routine with your tank you are probably ready to take it to the next level with Glass Catfish.

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