Ghost Glass Catfish (Kryptopterus vitreolus) are transparent, schooling fish that grow to 2‑3 inches (6‑8 cm). They need a 20‑gallon tank, dim lighting, and a group of at least 6. They’re peaceful but shy — not for every aquarist. Unlike most catfish, they don’t dig or eat plants. But they will hunt shrimp fry, so keep them away from breeding tanks.
Interesting fact: The natural transparency of Kryptopterus vitreolus made it popular as an experimental subject in science. These fish are often used as in vivo models for studies involving circulation, muscle function, pigment migration, neural regeneration, transplantation, visual processing, and even DNA immunization.
Quick Notes about Ghost Glass Catfish
| Name | Ghost Glass Catfish |
| Other Names | Glass Catfish, Asian glass catfish, Phantom catfish, or Ghost catfish |
| Scientific Name | Kryptopterus vitreolus |
| Water type | Freshwater |
| Tank size (minimum) | 20 gallons (~80 liters) |
| Keeping | Easy-Medium |
| Breeding | Difficult |
| Size | 2 – 3 inches (6 – 8 cm) |
| Optimal Temperature | 72 – 79°F (22 – 26°C) |
| Optimal PH | 6.5 – 8.0 |
| Optimal GH | 3 – 15 |
| Dwellers | Top to mid-dwelling |
| Nitrate | Less than 40 |
| Diet | Omnivore |
| Temperament | Peaceful |
| Life span | up to 5 years |
| Color Form | Transparent |
Taxonomy and Etymology
The genus Kryptopterus contains several similar species. Until 2013, all glass catfish were misidentified as Kryptopterus bicirrhis. Ng and Kottelat formally separated Kryptopterus vitreolus — the species you actually see in shops.
The name: “Kryptopterus” = Greek for “hidden fin” (they lack a dorsal fin); “vitreolus” = Latin for “made of glass”. Both fit perfectly.
Distribution and Habitat
The Ghost Glass Catfish (Kryptopterus vitreolus) is native to freshwater habitats in Southeast Asia (particularly in Thailand).
It occurs in rivers that flow into the Gulf of Thailand and river basins in the Cardamom Mountains. However, due to intra-species confusion, the precise distribution range of this species requires further clarification. For example, there are also unconfirmed reports that his species was found in Malaysia (Penang region).
In nature, The Ghost Glass Catfish can be found in a variety of habitats, including stagnant, slow, and fast-moving rivers, as well as murky or turbid waters filled with all types of aquatic plants.
Description of Ghost Glass Catfish
This is a relatively small fish species. In aquariums, the average size of adult Ghost Glass Catfish is about 2 – 3 inches (6 – 8 cm) in total length.
Distinguishing characteristics of Kryptopterus vitreolus:
- Body shape. It has a laterally compressed, elongated, slender body, and slightly curved tail.
- Color. This species is scaleless. It has a transparent body except for the head. Almost all internal organs are located in the head. Dorsal surfaces of the head and body often contain a yellowish tint. The spinal cord is visible as a distinct dark longitudinal line.
- Barbels. Maxillary barbels on its upper jaw reach beyond the base of the first anal-fin. They act as antennae and help it locate food.
- Barbels. There are two long barbels on its upper jaw (reaching to the 5th anal fin ray) and short mandibular barbels (about ¼ of eye diameter). Mandibular barbels are very short, approximately one-quarter of eye diameter.
- Snout. Snout length is about 29-35% of the head length.
- Eyes. The fish has relatively large eyes that contribute to its sensitive nature. The eye diameter is about 28-34% of the head length. They are located in the middle of the head, eyes are also visible dorsally and ventrally.
- Fins. Fins are transparent as well. Ghost Glass Catfish does not have a dorsal fin, but a single spine-like ray can be observed as a vestige of the dorsal fin. In contrast, the anal fin (48-55 anal fin rays) is elongated and extends from the pectoral fins to the tail. The caudal fin is strongly forked.
Interesting facts:
- According to the study, the fish shows flickering iridescence throughout the transparent body. When light passes through the tightly packed layers of muscle fibers, it creates a diffraction effect that produces a shimmering appearance.
- Ghost Glass Catfish are very good at sensing magnetic fields. It was shown that they have a specific ampullary organ for that.
Difference Between Kryptopterus vitreolus, Kryptopterus bicirrhis, and Kryptopterus minor
As I have already mentioned, the history of the taxonomy of Kryptopterus species involves a combination of morphological observations, geographic distribution analysis, and molecular studies to clarify its classification and relationship to other species.
| K.vitreolus | K.bicirrhis | K.minor | |
| Size | 2 – 3 inches (6 – 8 cm) | 5 – 6 inches (12 – 15 cm) | 5 – 6 inches (12 – 15 cm) |
| Color | transparent | more opaque | transparent with a light yellowish or blueish tint |
| Location | Thailand | Indonesia, Malaysia, and Thailand | Indonesia |
| Anal-fin rays | 48-55 | 46-67 | 60-64 |
| Available in hobby | common | very rare | extremely rare |
Lifespan of Ghost Glass Catfish
Currently, there is no data available on the maximum lifespan for Kryptopterus vitreolus in the wild.
However, if appropriately cared for, these fish can live up to 5 years on average.
Their lifespan greatly depends on the conditions they are kept in, how well you feed them, and how stressful your aquarium environment is for them.
Typical Behavior of Ghost Glass Catfish
Temper:
The Ghost Glass Catfish are generally known to be peaceful fish. They have a calm temperament and are not known to be aggressive or prone to nipping at other fish.
Sociality:
In their natural habitat, this species is usually found in groups that can number 100 or more, all facing the current in the same direction. They do not stray far from the group.
So, having a group of Ghost Glass Catfish in the aquarium can be beneficial for their well-being. It is generally recommended to keep them in groups of at least 6 or more individuals.
Keeping them in a group allows them to behave more naturally and reduces stress levels. They will feel more vulnerable and behave less actively and socially when kept in smaller groups or alone.
Activity:
Generally, Ghost Glass Catfish are very calm and not active fish. They will not dart around the tank instead they usually gather together in a tight-knit group around their favorite spot in the tank, minding their own business and not disrupting the movement of other fish.
They also do not exhibit typical catfish behaviors – they don’t dig or uproot what they can.
Ghost Glass Catfish are more active in the dark. However, in the daytime, they are very shy and skittish, especially, in the beginning. Once they are scared, they scatter and then return to schooling. They often hide in the plants or stay behind the driftwood and rarely come out unless it is a feeding time.
Note: Stressed fish may lose its transparent camouflage and become opaque.
At the same time, once accustomed to the aquarium conditions, when kept in a suitable group, their calm behavior can quickly change to highly active during feeding time.
Placement in Tank:
Ghost Glass Catfish usually stay in the top and middle areas of the tank.
Features:
- Social: Yes
- Activity: Low
- Placement: Top and middle dwellers
- Peaceful: Yes
- Nippers: No
- Jumpers: Yes
Feeding Ghost Glass Catfish
In the wild, this fish is a micropredator that feeds on small invertebrates and other types of zooplankton.
Like many catfishes, K.vitreolus is not picky when it comes to feeding and readily accept most frozen, dry or live foods. A varied and balanced diet is always recommended. Good options include:
- brine shrimp (artemia salina),
- artemia nauplii,
- cyclops,
- daphnia,
- mosquito larvae,
- moina,
- detritus worms
- vinegar eels,
- grindal worms, etc.
Frozen and commercial foods, such as:
- Fluval bug bites,
- Hikari first bites,
- TetraMin Crisps,
- any kind of really small crushed-up tiny flake food.
Some Feeding Tips:
Although Ghost Glass Catfish can adapt to feeding during the day, observation of their behavior has shown that these fish become more active during the dark hours. Therefore, an ideal approach would be to feed them at least in the late evening. This is their time!
Use the «five-minute rule». They are not prone to gluttony and quickly satisfy their appetite.
The main drawback of this feeding habit is that any food that falls to the bottom is rarely picked by them. Thus, if there is no cleaning crew (such as snails or shrimp) it can lead to ammonia, nitrites, and nitrate buildup in the tank. So, do not forget to regularly clean the substrate.
The first week struggle: Newly imported Glass Catfish often refuse dry or frozen food entirely. If they are hiding and not eating, do not panic. Offer live blackworms or glass worms. They usually cannot resist live movement. Once they start eating, you can slowly transition to frozen and dry foods.
Features:
- Diet Type: Omnivore
- Food Preference: Meat
- Feeding Frequency: Daily
Are Ghost Glass Catfish Plants Safe?
Yes, Ghost Glass Catfish are completely plant safe. They will not eat any healthy plants in the tank. This specie does not eat living plant material.
Keeping and Caring for Ghost Glass Catfish
To keep Ghost Glass Catfish healthy and happy, we need to understand their requirements and mimic their natural habitat. Stress will significantly reduce their lifespan.
While this species does not demand overly intricate care requirements, there is one thing to remember – these fish do not tolerate ammonia, nitrites, or nitrates really well.
So, it is still recommended to refrain from introducing them as the first occupants immediately after completing the aquarium cycling process. Wait for at least a couple of weeks until the balance is completely established.
Tank size:
The small size and relatively passive behavior of this fish should not mislead you when choosing a tank size for them.
Ghost Glass Catfish require a large tank, and there are a couple of important reasons for that, such as:
- it is easier to maintain water balance and parameters in larger aquariums.
- it is crucial to provide both hiding places and open areas without vegetation, driftwood, or other decorations for these fish.
Therefore, for a small group of 6-8 fish, you will need at least a 20-gallon (80 liters) tank. One Ghost Glass Catfish for every 2 – 3 gallons. More space = more stable water parameters, which they absolutely need.
Important: Ghost Glass Catfish are jumpers! So, it is imperative to take measures, for example: using a tank cover, lowering the water level, and using floating plants, which is essential to ensure their safety.
Water Parameters:
Temperature: Ghost Glass Catfish prefer water temperatures ranging between 72 to 79°F (22°C to 26°C).
pH: The ideal pH range is 6.5 to 8.0.
Hardness: The recommended general hardness (GH) range for these fish is 3 to 15 dGH. The recommended carbonate hardness (KH) range is 2 to 10 dKH.
Ammonia, Nitrite, Nitrate: It is important to maintain the ammonia, nitrite, and nitrate levels at 0 ppm, 0 ppm, and below 40 ppm, respectively.
Monitor the water parameters regularly and do water changes every week.
Lighting:
When the light hits them and they turn iridescent, it makes them look really cool. Unfortunately, Ghost Glass Catfish do not like bright light, it makes them stressed and they start hiding.
These fish enjoy remaining still in areas near the surface with dim lighting.
Water flow:
It was noticed that swimming against the slow current makes them more active.
Decorations and Plants:
Ghost Glass Catfish are shy and will appreciate plenty of hiding places, such as caves, driftwood, tall plants, and floating plants. They may retreat to these hiding places if they feel threatened or stressed.
| I would like to stress it again that placing Ghost Glass Catfish in open aquariums will be a huge mistake! The aquarium’s open layout proves unsettling for these timid fish. |
Note: Floating plants (such as Dwarf water lettuce, Frogbit, Duckweed) are ideal — they dim the light and make the fish feel secure. Driftwood and tall plants also help.
Related articles:
Acclimation (Crucial):
Ghost Glass Catfish are extremely sensitive to osmotic shock. If you just dump them from the bag into your tank, they will likely die within 48 hours. Use the drip acclimation method for at least 1–2 hours. Match the temperature and pH of the bag water to your tank slowly. I lost a whole batch this way early in my career. Do not rush the drip.
Quick setup checklist:
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Common mistakes with Glass Catfish:
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Common Health Issues
Glass Catfish are hardy once established, but they are sensitive to water quality. Here are the most common problems:
Stress and opacity
The fish lose transparency when stressed. Causes: poor water, small group, bright light, aggressive tank mates.
Fix the cause, and they regain transparency within hours.
Ich (white spot disease)
They are susceptible to Ich when stressed.
Fix: Because they are scaleless, do NOT use copper-based medications — it is highly toxic and will kill them. Instead, raise the temperature gradually to 86°F (30°C) over two days to speed up the parasite’s life cycle, and increase aeration. If the infection is severe, move them to a quarantine tank and treat with Methylene Blue.
Fungal infections
Look for cotton-like growths on the body.
Fix: Quarantine the fish and treat with antifungal medication. Improve water quality to prevent recurrence.
PreventionStable water parameters + varied diet + low stress = healthy fish. Weekly water changes (20-25%) are the best medicine. |
Breeding Ghost Glass Catfish
In home aquariums, breeding is extremely rare. Unless you have a dedicated setup and experience, don’t expect fry. To be more precise, there are only a few documented cases of successful breeding them in aquariums.
Almost all fish sold are wild‑caught. For example, Volume of the glass catfish exported in 2016 was 2,494,033 fish. So, there is a potential risk for populations of this species to become diminished in the future.
Note: Scientists have achieved success in breeding them artificially under laboratory conditions by using hormones to enhance oocyte maturation, followed by ovulation and spawning of fish in captivity.
Mating:
Ghost Glass Catfish do not have parental care or mate selection or anything.
Sexing:
The females are identified by large abdomens and red sex papillae.
According to some sources, the sexual identification of an individual can be also determined by its size (males are slightly smaller than females), although there is considerable disagreement regarding the accuracy of this method.
Eggs:
It can be presumed that they are seasonal egg scatterers like most other tightly-schooling fishes.
- the fertilized eggs of Ghost Glass Catfish are adhesive eggs,
- the diameter of eggs ranges from 0.75-0.85 mm.,
- all eggs are round in shape and bright yellow in color.
These fish are prolific breeders. Each female can carry from 100 to 700 eggs.
Incubation:
The incubation period for fertilized eggs to hatch is around 21.30 hours at 77 – 79°F (25 – 26°C) water temperature.
Larvae:
The newly-hatched larvae are about 2.5 mm in length. For the first 3 days, larvae consume the yolk. They grow pretty fast.
| Time | Size |
| Post-hatching | 2.5 mm |
| 6 hours | 2.8 mm |
| 1 day | 4.7 mm |
| 3 days | 5.7 mm |
| 5 days | 6.9 mm |
| 10 days | 7.8 mm |
Related article:
Suitable Tank Mates
The Ghost Glass Catfish are peaceful and delicate fish. It is important to choose tankmates that are compatible in terms of size, temperament, and water parameters. Here are some suitable tankmates for Ghost Glass Catfish:
Fish
If you still decide to keep this species in community tanks, some good options include:
- Neons,
- Endlers,
- Pygmy Cory,
- Danio Rerio,
- Guppies,
- Harlequin Rasboras,
- Dwarf Chain loaches,
- Swordtails,
- Southern platyfish,
- Mollies, etc.)
At the same time, it is important to understand that this species is a micro-predator, and it is not advisable to keep them in an aquarium with other fish that may have fry, as the catfish will prey on them. For instance, in one of my tanks, Ghost Glass Catfish nearly wiped out all the guppy fry.
Dwarf shrimp
It is not recommended to keep Ghost Glass Catfish with dwarf shrimp. These fish will leave alone adult shrimp but they will definitely hunt for shrimplets. Do not keep with breeding shrimp colonies.
Freshwater snails
Ghost Glass Catfish will not bother snails. In fact, freshwater snails can make good tankmates for this species, as they help keep the tank clean by consuming uneaten food and algae.
Avoid:
- Large and/or aggressive, and/or boisterous fish (such as Angelfish, Discus, Cichlids (too large, aggressive))
Keep them away from all types of crayfish and most types of freshwater crabs.
Related articles:
Frequently Asked Questions
How big do Glass Catfish get?
Adults reach 2 to 3 inches (6 – 8 cm). If your fish are larger, you likely have Kryptopterus bicirrhis, a different species that gets up to 6 inches. No myths, just what works.
Will Glass Catfish eat dwarf shrimp?
They won’t touch adult shrimp. But they are micropredators. They will hunt shrimplets. If you are breeding shrimp, keep these fish out of that tank.
How many Glass Catfish should be kept together?
At least 6. Preferably 10+. They are schooling fish. Keep them alone or in small groups, and they will stress out, hide, and literally lose their transparency. Period.
Are Glass Catfish aggressive?
No. They are extremely peaceful and shy. They won’t bother other fish. But they will get outcompeted for food by aggressive or fast-eating tank mates.
Can you breed Glass Catfish in a home aquarium?
No. Almost all Glass Catfish in the trade are wild-caught. There are a few documented cases of scientists breeding them using hormones, but zero successful home aquarium spawns. If you see eggs, they likely ate them or they were infertile. Don’t waste money buying “captive-bred” specimens; they don’t exist.
How to choose healthy Ghost Glass Catfish?
- Look for clear, transparent bodies (opaque = stressed or sick)
- Active schooling, not isolated or swimming erratically
- Intact fins, no redness or lesions
- Full bellies (not sunken)
References:
- London, Sydney, and Helene Volkoff. “Cloning and effects of fasting on the brain expression levels of appetite-regulators and reproductive hormones in glass catfish (Kryptopterus vitreolus).” Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology228 (2019): 94-102.
- London, Sydney. “The neuroendocrine control of feeding and reproduction in zebrafish (Danio rerio) and glass catfish (Kryptopterus vitreolus).” PhD diss., Memorial University of Newfoundland, 2018.
- Ng, Heok Hee, and Maurice Kottelat. “After eighty years of misidentification, a name for the glass catfish (Teleostei: Siluridae).” Zootaxa3630 (2013): 308-316.
- Khunjaroenrak, Waranyu, and Supat Ponza. “Embryonic and larval development of glass catfish Kryptopterus vitreolus (Ng and Kottelat, 2013).” Journal of Agricultural Research and Extension37, no. 1 (2020): 29-39.
- Khunjaroenrak, Waranyu, Pattreeya Ponza, and Supat Ponza. “Induced Breeding of Glass Catfish, Kryptopterus vitreolus (Ng and Kottelat, 2013).” Journal of Fisheries and Environment43, no. 3 (2019): 19-29.
- Ng, Heok Hee, and Maurice Kottelat. “A name for the glass catfish (Teleostei: Siluridae) revisited.” Zootaxa3640, no. 2 (2013): 299-300.
- Hunt, Ryan D., Ryan C. Ashbaugh, Mark Reimers, Lalita Udpa, Gabriela Saldana De Jimenez, Michael Moore, Assaf A. Gilad, and Galit Pelled. “Swimming direction of the Glass Catfish, Kryptopterus bicirrhis, is responsive to magnetic stimulation.” bioRxiv(2020): 2020-08.
- Fan, Xiujun, Xuezhi Zheng, Tong An, Xiuhong Li, Nathanael Leung, Bin Zhu, Tan Sui, Nan Shi, Tongxiang Fan, and Qibin Zhao. “Light diffraction by sarcomeres produces iridescence in transmission in the transparent ghost catfish.” Proceedings of the National Academy of Sciences120, no. 12 (2023): e2219300120.
Thank you for this great article!
What hormones did the scientists give to them to get the eggs to mature and the fish to then spawn?
Mine will readily come out at night or in a dark room in the blue light that is often labeled as “moonlight” mode. They look super cool in this lighting!
Mine have interesting social habits. When most are hidden in their log because of daylight, or some other reason, one or sometimes two of them will be outside of it as a lookout or guard. This one fish also watches for food. If he thinks he sees or smells food he will come scout it out, if it is food and it is safe, he will immediately go to “tell the others” that it’s safe to come out and there is food. When they do come out as a group for food, often times, one will stay behind in the log. The fish that stays behind rotates. It is not the same fish every time. I think this is so other kinds of fish won’t claim it for themselves.
One other interesting behavior I have noticed is that they will come to the glass near you sometimes to greet you. Usually the guard/lookout. I move my index finger up and down like a “mini wave” and my SAEs, the glass cat lookout, angels and betta will greet me in their own ways.
Finally, when my whole community tank got flukes the lookouts were sick with it and swimming irratically and jumping. Before I noticed that, they purposely came out to the very very front of the tank (not feeding time) and stared at me until I took notice and stayed there. I am a psychologist, so I study behavior and group dynamics… I swear it seemed like they were asking for help. I gave them a little food…. and they would not eat it. It wasn’t food they were asking for. The only time I see two of them come to the front like that and stare at me with all the lights on is when they need something badly.
They have come to me for attention, food, help from illness, etc.
I love these guys! They have a neat social group and the individual “duty” and personality of the lookout (s) is very cool to witness and interact with. I highly recommend people keep them. I would love to breed them so that we could eventually stop taking them out of the wild.
Mine used to spend a lot of their time out of the log hovering above it in the back of the tank…. but the SAEs decided they also liked this space… at first they shared it pretty well getting along well with one another. Then the saes kinda all moved in and dominate that area above the log. There is still one that stays out of the log though as a lookout.
Hi Dawn Marie Zimmerman,
The researchers used hormones like LHRH-a and domperidone to induce spawning. I linked the full study in the article where you can read all the details: https://li01.tci-thaijo.org/index.php/JFE/article/view/184082
Your observations about the lookout behavior are fascinating. I have never seen that level of social organization in my glass catfish. The rotating guard duty and the fish coming to the front when sick shows real intelligence. You are right that they were asking for help, not food.
Breeding them in captivity would be a huge contribution. Wild populations are getting hit hard by overcollection. If you can get a spawning to work, you would be doing the species a real favor. Start with that study I linked and work from there.
Best regards,
Michael
Hello Michael,
I cannot tell you how nice it is to be able to share these observations with someone who also finds it fascinating! They really are remarkable fish!
When I had them in a small quarantine tank on their own, they had a different working social structure that was much simpler, but interesting and kind of amusing. Each one wanted to be the one under the heater. (like a dog or cat in the fall laying by the heat register. lol) Only one of the larger ones could fit at a time. So that lucky fish would sit under there facing the other ones, guarding their spot. All of the others sat in a group facing the lucky fish… watching for an opportunity. When I would feed them, all the fish would eat… except the one under the heater…. that one didn’t want to lose his/her spot. lol I used to refer to them (as a group) as “The quorum.” Anyhow, the lucky one would not eat until they got so hungry they just couldn’t hold out anymore and then someone else would get a turn under the heater and choose to go hungry for a day or two.
They are now part of a community tank in a coralife biocube AIO 32 gallon, so the heater is in the back where they can’t get to it. lol. I have added to their ranks too. The new ones spent the better part of a day hiding among the plants but eventually they were welcomed into the fold that was already there.
One reason I found their behavior of the lookout seeing when there was food, when it was safe to eat and then leaving the food to go tell everyone else, so amazing is that I breed angelfish. “Wow, it’s safe out here and there is plenty of food! Let me go tell all the others so that they can eat too!” thought NO angelfish EVER! LOL For an angelfish it’s more like “Mine! Mine! It’s all Mine!!!” lol It amazes me how different fish can be from one another. Between species and sometimes even individually.
Thank you again for the link. I must have gazed right over that when reading the article. I am not set up quite yet to do a glass cat only tank, but I am planning on it. At the moment I am dealing with a stand that wasn’t built correctly for multiple smaller tanks and trying to figure out how I can make it work for what I want.
Thanks again,
Dawn
Hi Dawnm,
That heater behavior is brilliant. I have never seen that level of stubbornness in fish. The lucky one starving itself just to hold the warm spot shows real dedication to comfort. And “The Quorum” is the perfect name for that group dynamic.
The comparison to angelfish is spot on! I breed angelfish too and they are the most selfish fish in any tank. If one finds food, it will chase everything else away. Glass catfish are the opposite. That cooperative behavior is rare in the aquarium hobby.
Take your time with the stand situation. When you do set up that glass cat only tank, you will see even more interesting behaviors without other species competing for space. They get bolder in larger groups of their own kind.
Let me know how the dedicated tank works out when you get it running.
Best regards,
Michael
I’m really glad to see your comment. I was pleasantly surprised to find that the behavior of my fish is very similar to the habits you described. I had previously thought that the fish acting as a guard wasn’t eating, which had me quite worried.