Glass Catfish: Complete Care Guide & Species Profile

A group of glass catfish swimming through aquarium plants
Dr. Mollie Newton
Published by Dr. Mollie Newton PHD| Senior Editor
Last updated: July 12, 2024
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The glass catfish, a cherished tropical freshwater species, offers flexibility for various aquarium settings, ensuring endless enjoyment as you watch their group dynamics. Given the somewhat specific needs of this breed, we’ve gathered information from our most reliable sources to provide you with this straightforward guide. Continue reading to gain a comprehensive understanding of how to care for your glass catfish!

Article Summary

  • Glass catfish have completely transparent bodies with a black line representing their spine, lack a dorsal fin, and have forked caudal fins which makes it challenging to determine their gender.
  • They are sensitive and prone to diseases like Ich, fungal infections, dropsy, fin/tail rot, and ammonia poisoning.
  • Breeding glass catfish is extremely difficult due to the challenges of sexing, shyness, and specific breeding conditions.

Species Overview

Common namesGlass catfish, ghost catfish, skeleton catfish, phantom catfish
Scientific nameKryptopterus vitreolus
SpeciesK. vitreolus
Size2.5-4 in
Lifespan7-8 years
FamilySiluridae
GenusKryptopterus
DistributionSoutheast Asia
ColorNone/Transparent
DietOmnivore
TemperamentPeaceful/shy
Minimum tank size30 gallons
Place in tankMiddle
Care levelModerate
BreedingDifficult

History and Background

If you are trying to create a more diverse background in your aquarium the glass catfish’s history is definitely worth sharing to visitors and spectators alike.

Origin

The glass catfish, also called ghost catfish or phantom catfish, has mainly been found in Thailand with a few cases reported in Malaysia and Cambodia. In their natural environment you can most often find them in moderately flowing rivers and river basins from the top of the Cardamom mountains to the Gulf of Thailand.

FUN FACT

The glass catfish (Kryptopterus vitreolus) used to be classified as Kryptoptreus bicirrhis, a larger and more aggressive species. It was only using DNA analysis that they were determined to be two different species, thus the glass catfish gaining the new scientific name Kryptopterus vitreolus.

Glass catfish became popular fish in the aquarium trade in the 20th century due to its unique appearance. Its late entry to the aquarium hobby is likely because people could not see it unless the light shone through the water just right.

Appearance

many glass catfish swimming together
(1) A Group of Glass Catfish Swimming In An Aquarium

The glass catfish gained its popularity due to its odd but characteristic traits. It’s rare that a fish is completely see through and has no dorsal fin, and even rarer that you can keep it in your home aquarium!

What do glass catfish look like

Glass catfish are unique fish in the fact that they possess no color pigment, making them completely transparent. You might notice a black line running from their head to the bottom of their caudal fin, this is actually their spine. Additionally, you can see their internal organs and watch as their food digests after feeding time.

This freshwater fish has no dorsal fin and forked caudal fins. They have barbels that extend straight out from their head unlike most catfish who’s barbels run alongside their bodies while they swim. Their hardly visible tail fin is fast moving and hard to catch sight of as they swim actively throughout your tank.

How to tell the gender of a glass catfish

It is unknown how to gender this fish species. Despite having a transparent body no one has been able to identify genitalia. This is one reason why breeding this freshwater fish is so difficult.

Color/Variety

There is only one coloration of this fish: transparent. Depending on the environment and lighting you might see this transparent fish be slightly tinted blue or green as it swims past certain decorations and plants.

The transparency of this fish comes from the fact that it is scaleless…

The transparency of this fish comes from the fact that it is scaleless (like most catfish) and its body lacks a color pigment. In its natural habitat this is a defense mechanism for avoiding predators.

How big does a glass catfish get

Average glass catfish size ranges from 2.5 to 4 inches, though it usually stays on the smaller size.

How fast do glass catfish grow

Like most other fish, glass catfish grow rapidly when they are young and slow down as they get older. However, each individual fish grows at a different rate so it is hard to generalize a growth rate.

Temperament and Tankmates

Glass Catfish Swimming With Other Fish Species
(2)Glass Catfish Swimming With Other Fish Species

While glass catfish are shy they do enjoy having many tank mates in the tank and do well with others that are similarly sized.

Can glass catfish be kept alone?

No, glass catfish need to be kept with others of their kind. These timid fish will be constantly stressed if kept alone.

How many glass catfish should I get?

To form a proper school and keep your fish happy you should keep at least 5 or 6 of this fish species in a single tank. A smaller school might produce more aggressive fish that will bully others in their group.

How many glass catfish should be kept together?

You can keep as many glass catfish as you have room for, however the ideal number is around 5 or 6. You should allot 5 gallons for every single glass catfish, so a total of 25 to 30 gallons.

Are glass catfish fin nippers?

No, this peaceful fish will likely stay far away from other fish species and will not attempt to interact with them. However, you might notice when you introduce the schooling fish that they are nipping at each other. This is to establish a hierarchy and will soon subside.

What fish can live with glass catfish

Other fish that are of similar size and have a calm nature would make great tank mates for the ghost catfish. Additionally, because of glass catfish’s shy nature you should be sure to have plenty of hiding spots for them to escape from other fish.

Top 5 Compatible tank mates

  1. Guppie Fish-this is perhaps one of the only tanks that guppies will do well in and not become feeder fish
  2. Tetras– while one of the more aggressive small fish, the tetra’s colors will compliment that of the phantom catfish
  3. Mollies-another schooling fish that does well in a community tank and similar conditions
  4. Dwarf Gourami-a peaceful and small fish that’s coloring and personality will add vibrancy to your tank.
  5. Harlequin rasbora– another characteristic Southeast Asia fish species that may interact with the glass catfish as a wild fish

Other catfish, such as Corydoras or the very peaceful Two Spot Mystus, would also make good tank mates. Additionally, the playful yoyo loach does well with these small, shy creatures.

Tank Requirements

A Planted Freshwater Aquarium With Different Fish Species
A Planted Freshwater Aquarium With Small Fish Species

When keeping this species it is necessary to have strict water parameters or else you risk having fish with growth defects.

Tank Size

You should alot a minimum of 5 gallons per glass catfish. For a school of 6 they need a minimum tank size of 30 gallons to give them enough space to swim.

Water Parameters 

Tank Size>30 gallons
Water TypeFreshwater
Water Temperature75-80
Water pH6.5-7.0
Water hardness8-10 dGH

Tank setup:

What kind of substrate to use for glass catfish

Unlike other catfish that spend most of their time along the bottom of the tank, glass catfish will swim throughout the middle of the water column. However you should choose soft substrate so they can scavenge along the bottom of the tank as they choose.

Additionally, you can add dark colored substrate to your home aquarium to make it easier to see your glass cats.

Should I add a filter to my tank

We strongly suggest using a filter when keeping glass catfish as you will need to maintain strict water parameters to keep them happy.

Do I need a pump

A filter alone is not enough to provide enough water flow for this fish so we suggest finding a pump with an adjustable flow rate. This will not only ensure proper water flow, but also aerate your aquarium, which is especially necessary if you plan to keep vegetated tanks.

Is a tank Water heater necessary

As this species is a tropical fish you will likely need a water heater to keep a consistent temperature throughout the water column in your aquarium.

What kind of tank lighting should I use

These fish are avoidant of bright lights and easily stressed when put in the spotlight in your aquarium. Instead we suggest using bulbs that have a soft glow. This will provide closer resemblance to their natural environment.

Do glass catfish like a planted tank

The glass catfish is a good fish to use live plants with in your aquarium. They will enjoy the extra hiding places and are unlikely to nibble on the leaves of the aquarium plants.

For aquarium owners that are new to aquatic plants we suggest using java moss and hornwort as they are hardy and easy to keep. Additionally, you can add floating plants such as Amazon Frogbit or water lettuce to provide a shady covering over your tank and decrease light penetration.

Diet and Health

Live Brine Shrimp, fish food
(3) Live Brine Shrimp As Fish Food

These fish are omnivores, but their diet is very tricky to perfect. A high protein diet with supplemental greens and veggies is the best diet for these picky eaters.

What do glass catfish eat

While glass catfish are omnivores they are very selective feeders. In their natural habitat glass catfish are known to eat small fish, insects, insect larvae, small worms, and other small invertebrates as well as plant matter.

What to feed glass catfish?

To replicate their natural diet you should try to feed your glass catfish a high protein diet consisting of frozen or live food. Options include grindal worms, daphnia, frozen brine shrimp, and commercially available food.

Generally, the glass catfish is a picky eater and does not like fish flakes or pellets. You will have the best luck getting them to eat live food, but frozen food and freeze dried food are also worth a try. When deciding what food your fish prefers, watch to see if it has a positive feeding response such as swimming straight towards the food when dropped in the tank.

TIP

As omnivores you should also include some plant matter in your glass catfish’s diet. If you have tank mates they will likely also need supplemental greens and my preferred method is just dropping a leaf of blanched spinach or lettuce in the tank every 3 days and allowing the fish to graze at it.

How often to feed glass catfish

You should shoot to feed your glass catfish once to twice a day, with supplemental high-protein food given 2 to 3 times a week. The exact schedule can be determined by your availability.

How much to feed glass catfish?

We recommend using the three minute rule when feeding your glass catfish. This is when you drop a few pieces of food into a tank and start a timer. Continue dropping food morsels as your glass catfish eats them but stop once the timer is done.

Because of their picky eating habits you may find that three minutes is too short of a timeframe and choose to increase it to five minutes.

Are glass catfish hardy?

No, the glass catfish is quite sensitive and requires excellent water parameters, a very small water temperature range, and is easily stressed out by too many obstacles such as tank mates, decor, and plants.

Common diseases of glass catfish

Because of their high maintenance and strict water quality needs it is very easy for these fish to catch a disease. We have noted the five most common below.

  • Ich-anyone who has had a tank for any period of time knows that ich poses a serious threat to fish. Ich symptoms include white spots developing over the body and your fish rubbing against decorations as if it is itching. Treatments can include aquarium salt and medication that will specifically target ich.
  • Fungal infections-Fungus covers a wide variety of diseases that are present in most water sources and will target stressed fish. Poor water quality can make fish especially susceptible to developing fungus. Treatment includes treating with anti-fungal medication and aquarium salt as well as water changes.
  • Dropsy-another serious disease that is often mistaken for bloating or constipation. The tell tale sign of dropsy is that the fish’s scales stick out like a pine cone. However in fish without scales (like the glass catfish)it can be extremely difficult to identify symptoms. Treatment includes quarantining, aquarium salt, and broad-spectrum antibiotics.
  • Fin/tail rot– another disease that is extremely hard to identify the symptoms of in the glass catfish. Symptoms include a ragged, uneven appearance to the tail or fins of the fish which are lined with white fuzz. Fin rot treatment includes broad spectrum antibiotics, aquarium salt, and anti fungal medicine for potential secondary fungus infections.
  • Ammonia poisoningcaused by poor water quality ammonia poisoning is caused by the buildup of ammonia in your aquarium to an extreme level. Symptoms include redness of skin, lethargy, and loss of appetite. Treatment is removing affected fish from the tank immediately and re-cycling your aquarium.

How long do glass catfish live?

In ideal conditions the glass catfish can live 7 to 8 years in captivity.

Breeding

A Pair of Glass Catfish
(4) A Pair of Glass Catfish

Breeding is extremely difficult and not recommended for this species.

Can you breed a glass catfish?

It is extremely difficult to breed the glass catfish in a home aquarium and very few people have been successful at it. One of the many issues is that it is almost impossible to sex this fish. Additionally, they are very shy and become stressed at the slightest change in environment, making community tanks not ideal for breeding glass catfish. The final challenge is that these fish breed during monsoon season, meaning you have to replicate those conditions in your aquarium.

How to breed a glass catfish?

You should move your fish that you are intending to breed into a separate aquarium 2 to 3 weeks prior to starting the process. It is best to have at least 5 fish in a breeding tank to increase the chances of having a mating pair.

Begin by lowering the water level in your aquarium so you have room to fill it to stimulate the rainy season and begin feeding your breeding pairs a high protein diet including mosquito larvae, brine shrimp, and daphnia. To simulate breeding conditions you will have to slightly alter the water parameters by lowering the temperature range down to 72-75. Begin to add water to the tank (about 5%) to replicate rainfall.

TIP

Some breeders have reported having more success when using a watering can to simulate rain falling.

Continue to observe the female glass catfish in your aquarium, if it is effective the females bellies will begin to swell with eggs. Once the fish spawn, remove them from the breeding tank.

The eggs will take a few days to hatch, once they begin their free swimming lifestyle you can begin to feed them baby brine shrimp and infusoria. The young glass catfish should be kept in a separate tank without any other species tank mates until they are adult sized.

What do glass catfish eggs look like

Much like the glass catfish coloring their eggs will be white and almost transparent.

Is the glass catfish for you?

Keeping a glass catfish will definitely make you the talk of the aquarium trade and is an interesting addition to your aquarium that many people do not know about.

Conclusion

The glass catfish makes a wonderful addition that will definitely add the wow factor to your aquarium. Though they are semi difficult to keep, we think this amazing species is worth the extra effort.

(1) Martin Fisch, CC BY-SA 2.0, via Wikimedia Commons
(2) CONTERALLY at Italian Wikipedia, CC BY 3.0, via Wikimedia Commons
(3) Saul Dolgin, CC BY 2.0, via Wikimedia Commons
(4) JC7001, CC BY-SA 2.0, via Wikimedia Commons

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