Glass Catfish
(Kryptopterus bicirrhis & minor)

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The glass catfish you will find for sale online or at your local fish store is a commonly overlooked misnomer. There is a distinct possibility that many retailers are not even aware of the fact that they are not offering you an actual “glass catfish.” There are two separate species that fall within the realm of glass catfish. Both are of the family Siluridae and indigenous to the same region of the world. Both are transparent. And both have two characteristically long brabels extending from between their noses and mouths. They are so identical in appearance that they were classified as a single species until 1989. This may explain the general confusion about the true identity of the fish on the other side of the glass.  

The original scientific classification for these aquatic oddities was Kryptopterus bicirrhis. Despite what you may assume, this species was not scientifically described for its transparent appearance. Their name, broken down to it ancient Greek components, literally means Kyptos (hidden) and Pteryx (fin). This classification refers to the greatly reduced size or very frequently, the complete absence of a dorsal fin. This is the true “glass catfish.” Eventually it was determined that some of these fish grew substantially larger than others. This discovery led to a second species classification; K. minor. The Kryptopterus minor is known in laymen’s terms as a ghost catfish.  

Glass catfish are larger and significantly more aggressive than their smaller counterparts. Glass catfish are rarely, if ever, exported. It is the K. minor or ghost catfish that you will see in fish stores. Their reduced size and more mild mannered temperaments make them the much preferred choice of the two by the aquarium trade industry. As far as the aquarium trade is concerned, these are “glass catfish.” Although glass catfish is by far the most prevalent, these fish are also sold by their real names, ghost catfish, as well as the trade names; phantom catfish, glass ghost catfish and ghost fish.

Regardless of what they are called, glass catfish are native to East Asia. They inhabit the large rivers and turbid waters of Borneo, Sumatra, the Malay Peninsula and the Chao Phrayaa and Mekongg drainage basins. They live near the shorelines in water with strong currents. They are diurnal predators (active in daylight) whose diet consists mainly of true water bugs in the wild.

Glass catfish are some of the most unusual fish you can buy for a freshwater aquarium. Their bodies are totally devoid of scales. If they were not, the fact that their skin and meaty tissue are transparent would go completely unnoticed. These fish strike instantaneous awe in any child that sees one. It is quite common to hear a gasp followed by, “Look you can see right through it.” There is something absolutely fascinating about being able to see right through a creature, down to it bones and internal organs and then out the other side of its bodies. If you examine one up-close with a magnifying glass, you can literally see its heart beat. Perhaps what is even more captivating is that these see through fish sheen with an iridescent glow when they are struck by light at the right angel.
 
Glass catfish have a docile demeanor. They make good community fish as long as they are in the company of similarly mild mannered fish. Glass catfish are a medium sized fish. They grow to about four inches in length. They are mid-tank swimmers.

The schooling instinct runs extremely strong in these creatures. A glass catfish will frequently perish without another member of its own species present. If you have two and one dies, it is not uncommon for the other to die shortly thereafter. It is advisable to keep at least four of them at a time. Six or more will more adequately address their social habits and allow you to observe then behaving as they would in nature.  

Glass catfish are every bit as fragile as their name. They have been known not to survive the trip home from the fish store. This is most probably stress induced from the rapid transition form one environment to another. Once home, their chances of long term sustainability are significantly increased by a heavily planted aquarium. They are a shy species and will fare much better given plenty of places to hide. Live plants are preferable but plastic plants, rock work and aquarium décor will suffice.

Here are some serious tips to consider when first introducing glass catfish to your aquarium. They will frequently sink to the bottom and lay on their sides, looking quite dead for all intents and purposes. Do not panic. This is a very high strung and easily intimidated animal. They will rise from the bottom and start swimming around once they become more confident with their new surroundings. The stress levels of initial introduction can be significantly reduced by transitioning these fish from a very dimly lit room to an unlit aquarium after dark. These fish prefer dim lighting and will feel less panicked if they are introduced to a dark aquarium. This is especially important if you purchased your glass cat fish online. They will almost certainly arrive to you encased in a protective styrofoam box. They are in the dark. Keeping them in the dark will be of great benefit to initial acclimation.

Glass catfish prefer neutral to slightly acidic water (pH 6.8-7.0). They are better suite to water temperatures a little cooler than some other tropical fish. The ideal temperature range is 70-79 °F. They function best in subdued lighting. Have a filtering system that provides plenty of water flow to simulate the currents they are accustomed to living in will prove beneficial. Under premium conditions glass catfish have a life expectancy of 6 to 8 years. Once again, these are delicate creatures. A sure sign that your glass catfish is not faring well is a loss in its transparent qualities. Glass catfish turn from clear to a milky white when they die. If you notice any loss of transparency, check you water parameters immediately. If the water parameters prove acceptable, check for body damage or signs of common tropical fish ailments and parasitic infestations.

Glass catfish  are egg layers. Attempts to breed them in captivity have thus far failed. So the ones you see at the fish store have been recently removed from their native environment. They may very well suffer from escalated stress levels until they adapt to their new surroundings. Your job is to lessen those stress levels to the best of your ability.

Remember, these are not commercially raise fish. In the wild their diet consists primarily of true water bugs. These omnivores are accustomed to eating live food. In order to help them adapt to their new environment you should start out by feeding them brine shrimp. Small insect larvae are preferable if you can find them. They will eventually learn to eat freeze-dried, frozen food and possibly even tropical fish flakes. But you still want to supplement their diet with live protein to insure their continued hardiness. These are, after all, rather fragile creatures.