Kryptopterus vitreolus, commonly known as the Ghost Glass Catfish, is a fascinating fish species that has gained some recognition in the fish-keeping hobby. Despite its relative popularity, this fish is not widely distributed, making it a unique addition to an aquarium collection.
This species is not particularly demanding in terms of care requirements and can be recommended even for beginners. However, it is important to note that the Ghost Glass Catfish’s shy nature and calm behavior may not be suitable for every aquarist.
Whether you are a beginner or an experienced aquarist, in this article, you will find comprehensive information about Kryptopterus vitreolus that will provide you with the necessary knowledge to successfully keep and care for this intriguing fish species.
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 of Ghost Glass Catfish
The genus Kryptopterus contains several small catfish that exhibit similar morphologies.
In fact, in the early 2000s, there was some taxonomic confusion surrounding Kryptopterus vitreolus and other closely related species, Kryptopterus minor and Kryptopterus bicirrhis. Initially, all these species were misidentified and considered Kryptopterus bicirrhis or synonymous in the past.
In 2013, this long-standing misidentification was resolved when Ng and Kottelat introduced the glass catfish as a distinct species, known as Kryptopterus vitreolus.
Etymology of Kryptopterus Vitreolus
The genus name, Kryptopterus, is derived from the Greek words ‘Kryptos’, meaning ‘Hidden or concealed’, and ‘Pteron’, meaning ‘Fin’.
The species name ‘Vitreolus’ is derived from the diminutive form of the Latin adjective ‘Vitreus’, meaning ‘Made of glass’, in reference to its transparent body.
This name refers to the scale-less and transparent appearance of the fish, which also gives it the impression of having hidden or invisible fins.
Distribution of Ghost Glass Catfish
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).
Habitat of Ghost Glass Catfish
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 accepts
most foods given to aquarium fishes
In an aquarium, they will usually accept food of all kinds (live, dry, or freeze-dried) as long as it is adapted to their mouth size. A varied and balanced diet is always recommended.
Ghost Glass Catfish are not picky eaters, they will eat live food:
- brine shrimp (artemia salina),
- artemia nauplii,
- cyclops,
- daphnia,
- fruit flies,
- mosquito larvae,
- moina,
- detritus worms
- vinegar eels,
- grindal worms, etc.
They also accept frozen and commercial food as well, such as (links to Amazon):
- 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, nitrite, and nitrate buildup in the tank. So, do not forget to regularly clean the substrate.
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.
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: Dwarf water lettuce, Frogbit, Duckweed, and other floating plants are excellent at hiding light and providing these fish with the lighting they prefer.
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Breeding Ghost Glass Catfish
Kryptopterus vitreolus is rarely bred in home conditions, to be more precise, there are only a few documented cases of successful breeding them in aquariums.
Almost all fish sold in stores are caught in the wild. 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 h 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 |
Ghost Glass Catfish and Suitable Tankmates
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: Platies, Neons, Endlers, Pygmy Cory, Danio Rerio, Guppy, Harlequin Rasboras, Dwarf Chain loaches, Swordtails, 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 aquarium, 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.
-
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 fishes.
- Keep them away from all types of crayfish and most types of freshwater crabs.
Related article:
In Conclusion
The Ghost Glass Catfish are one of the most unusual members of the catfish family. They have a truly fascinating appearance, making them a mesmerizing sight in an aquarium.
However, if you are fond of colorful and active fish that strive to always be in sight, this particular species may not be suitable for you.
Ghost Glass Catfish are very calm fish that more closely resemble ghosts hiding in a corner than vibrant and boisterous fish.
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.
Common Names: Glass Catfish, Ghost Catfish
glass catfish’ or ‘ghost catfish’