Catfish of the Month Right Arrow February 1997 • Article © Julian Dignall, uploaded February 01, 1997

Glass Catfish, Asian Glass Catfish, Indischer Glaswels (Germany), Indisk Glasmal (Sweden), Phantom Catfish - Kryptopterus vitreolus   Ng & Kottelat, 2013

Most people start keeping catfish for one or both of two reasons. The first is the misguided and widely perpetuated myth that they are all excellent scavengers and will compensate for over-feeding, under filtration, eat algae, eradicate snails and combat a multitude of aquatic evils. This is perhaps true, to varying degrees, of some catfish. I believe the other reason people start keeping catfish is that they are unusual. Glass catfish are one of the most unusual of an unusual bunch. You can see right through them.

I started with a trio of these fish. They were timid, but fed well and kept themselves to themselves. It struck me that these would be ideal fish to keep with Discus if they could tolerate higher temperatures that Discus prefer. I transferred my trio to the Discus tank successfully and increased the shoal to seven individuals who happily coexisted with the Discus, assorted Tetras and Corydoras also present.

True glass catfish are completely transparent. If you look at one through a magnifying glass you can see the heart beating within the silver reflective sac that houses all the fishes organs. This species is also unusual amongst catfish in that it is a midwater swimmer and is inactive at night. This is not your average catfish. Indeed, one of the most interesting (probably because unexplained) aspects of this odd fish is that almost immediately following death, the fish loses its transparency becoming milky white. This suggests that something Glass Catfish do while alive produces or maintains the transparent effect.

I have also seen the African Glass Cat - Parailia pellucida - labelled as the Glass Cat, so always keep your eyes peeled when you look at a tank of these fish for sale. While on the subject of keeping your eyes peeled, some of you may have noticed that we have labelled this fish with a scientific name different from that you find in most hobbyist books. It appears that the glass catfish has been misidentified for a long time now as Kryptopterus bicirrhis, this fish grows much larger (up to 10") and has more rays in its anal fin. It is quite possible that, at some point in the last 30 years or so, K. bicirrhis was the fish imported into the aquatic trade as the Glass Catfish. Given the lack of 10 inch Glass catfish around today it is probably safe to say this isn't the fish we encounter most frequently in the shops.

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Jump to next section Cat-eLog Data Sheet
Scientific NameKryptopterus vitreolus  Ng & Kottelat, 2013
Common NamesGlass Catfish
Asian Glass Catfish, Indischer Glaswels (Germany), Indisk Glasmal (Sweden), Phantom Catfish
Type LocalityThailand: Trat Province, Amphoe Khao Saming
PronunciationCry top ter russ. - vih TREE oh luss.
EtymologyKryptopterus: From the Greek kryptos, meaning hidden and pteryx, meaning fin; in reference to the reduced or absent dorsal fin of this group of fishes. From the diminutive form of the Latin adjective vitreus, meaning of glass, in reference to the transparent appearance of this species in life (which gives this species its common name of glass catfish).
Jump to next section Species Information
Size 80mm or 3.1" SL. Find near, nearer or same sized spp.
IdentificationSometimes - the African Glass Cat, Parailia pellucida - is labelled as the Glass Cat, so always keep your eyes peeled when you look at a tank of these fish for sale. We have labelled this fish with a scientific name different from that you find in most hobbyist books. It appears that the glass catfish has been misidentified for a long time now as Kryptopterus bicirrhis, this fish grows much larger (up to 245mm) and has more rays in its anal fin. It is quite possible that, at some point in the last 30 years or so, K. bicirrhis was the fish imported into the aquatic trade as the Glass Catfish.
Jump to next section Habitat Information
DistributionKnown from the short, coastal drainages in peninsular Thailand debouching into the Gulf of Thailand south of the Isthmus of Kra (from about 8°38'N to 6°2'N), as well as similar rivers draining the southeastern face of the Khao Banthat (Cardamom) Mountains in southeastern Thailand.
Thailand Waters (click on these areas to find other species found there)
Show it on a map (Click the map-icon to show/hide map of species distribution)
pH5.5 - 6.5
Temperature21.0-26.0°C or 69.8-78.8°F (Show species within this range)
Other ParametersSlow moving water providing areas of current and areas of still water. This fish rests in still water and stalks in gentle current.
Jump to next section Husbandry Information
FeedingWill usually take prepared foods especially if moved by a current. Likes live brine shrimp and larger established fish relish bloodworm.
FurniturePlants are necessary to make this fish feel at home. Floating plants that diffuse overhead light help but are not mandatory. Open swimming space is required, as this fish favours swimming freely at feeding.
CompatibilityPeaceful, will eat very small fry, but otherwise harmless.
Suggested TankmatesKeep in a shoal of at least four but preferably six or more individuals. Such a shoal of glass catfish will do well with small tetras, rasboras or danios. Provided its tankmates are not too boisterous this fish will do well in well planted community aquaria.
BreedingLittle is known about the specifics of reproduction, appears to be an indiscriminate egg scatterer. See Shane's World article. .
Jump to next section Further Information
ReferencesBiogeographical Society of Japan (Tokyo), pp 309, Figs. 1-2
Registered Keepers(1) Jools, (2) snowball (k: 25), who also notes: "They split up into two groups during the day, both sheltering under overhang wood. At night they all school along the front of the tank in the current. I feed them at night, but they will come out during the day when they smell food.", (3) kcmt01, (4) Persephone, (5) Moontanman, (6) adimeatatime (k: 10), (7) gage, (8) H (k: 5), (9) Richie Hell, (10) Marsdinho, (11) Blairc (k: 6), who also notes: "These timid Cats are very good eaters, and can be fed on a diet of flakes, frozen and live food. They are extremely sensitive to changes in water conditions, and will go white when stressed. These fish enjoy having peaceful tankmates and a good plant. These Catfish are my favourite fish, and have been through the thick and thin of my fishkeeping career.", (12) Igowoof, (13) artemis1, (14) spot86t, (15) pleco_keepin_bear, (16) bang (k: 2), (17) mouseninja (k: 3), (18) lene.keiserud, (19) Plecofanatic1989 (k: 3), (20) nooneknows (k: 6), (21) c arri10 (k: 5), (22) theonetruepath (k: 2), (23) fraggle (k: 5), (24) jb92 (k: 3), (25) Plunt, (26) loachy_406 (k: 4), who also notes: "They are quite active when the light is off, but otherwise they stick to the shade, or in the hollow rock.", (27) ZedMuir, (28) mini-fée, (29) mante-religieuse (k: 6), who also notes: "2 died from ICH 2 weeks after I got them. 6 are perfectly healthy", (30) AimsPink, (31) griffl, who also notes: "One expired on 9-4-08. Second expired on 12-15-08 ", (32) iam1ru12 (k: 4), (33) ash104a (k: 6), (34) fishmosy (k: 4), (35) Nick44 (k: 5), who also notes: "Bought from Ely Aquatics. Absolutely perfect adult specimens. Feeding on flake and Freeze Dried Tubifex", (36) HX67 (k: 20), (37) LLLL, (38) kiwiplymouth, (39) andycapdnz (k: 5), (40) fischkringli (k: 6), (41) boogie (k: 6), (42) blaqksotu16 (k: 6), (43) acidise, (44) mangopleco, (45) allpuffedup (k: 5), (46) Irish Goliath, (47) Industrial (k: 7), who also notes: "School tightly with aggressive fish in the tank (such as angels), but are much calmer with a gentle current and peaceful fish. Some will frozen bloodworms out of my hands and some have even been slightly territorial towards other species.", (48) coelacanth, (49) ocnluv13 (k: 2), (50) bronzefry, (51) L number Banana (k: 3), who also notes: "Can be hand fed with frozen brine shrimp, they tickle your palm :-) Very cool fish to watch, sometimes bicker among themselves and will often chase larger tetras away from food. Update winter 2012: lost three when lid broke and they jumped out.", (52) judeblackburn (k: 6), (53) roadkingray, (54) kouen (k: 9), (55) djechoskittykat, (56) Hansen (k: 2), (57) Dee (k: 5), (58) Grimfilth (k: 7), (59) Dalek Tzet (k: 2), who also notes: "I cannot get groups of these to thrive, they always whittle down to one or two, who are fine for months. add another, instant death. I can't win. They like to glare balefully from under plants, eat anything.", (60) milutin (p: 2), (61) Anthonyck (k: 2), who also notes: "Lost one of original six early on. Remaining species are doing well, though a couple are growing much more rapidly than others. Inconsistent shyness; seem very sensitive to any changes, water cleaning, noises, etc. June 2012: lost one when moving tank. Did not get water temp balanced quickly enough, and a few kryptopterus seemed to "sink" because of the temperature change. One did not survive this disturbance; all others recovered completely. Feb 14 2015 - two adults remain in the 75 gal. Again the move claimed a few.", (62) Quo (k: 4), (63) arapaimag (k: 6), (64) browny85, (65) fleshwound (p: 2, k: 3), (66) Apostolis (k: 2), (67) indiCa, (68) Sfamnun (k: 9), (69) AvengedKombat, (70) linuxrulesusa (k: 2), (71) 000, (72) in_the_seance (k: 8), (73) DKcincy (k: 5), who also notes: "These guys went nuts when i offered them frozen brine shrimp", (74) Rebah, (75) Sean B, (76) crazy4bettas (k: 6), (77) dmcat (k: 7), (78) Valb68 (k: 6), (79) kvnbyl, (80) glasscats, (81) VickyEll7 (k: 4), (82) dpm1 (k: 5), who also notes: "Kept in a mixed community where they are pretty much the biggest fish. They hover in the rear but aren't shy or skittish including hand feeding, unmoving during maintenance, and will come forward as soon as the lights dim (and sometimes before, especially if feeding). Can be sexed when carrying eggs but other times almost impossible. Unfortunately didn't see any actual breeding or egg laying.", (83) bekateen (k: 5), (84) Johnny579, (85) Atmichaels (k: 6), (86) marco0raimondo, (87) fishy1 (k: 3), (88) datfish (k: 8), who also notes: "Kept in a dense riparium that receives only natural sunlight, so longer dawn and dusk. The main shoal breaks into three smaller ones during the day, with two swimming only six or so inches apart and a pair accross the tank. At dawn they all group together in the densest part of the plants. During their peak sunlight hours they are more active, exploring the planted sections. During dusk they come out into the open to search for food.", (89) MattHunt (k: 7), who also notes: "Shoal size 7. Newcomers took 36 hours to come out from the plants. Lost 1 15/2/18 - I suspect age as was swimming tail down for a week before hand but not discoloured.", (90) Lycosid (k: 13), (91) caninesrock, (92) CoryCats655 (k: 6), (93) OregonOutdoorsChris (p: 2, k: 6), who also notes: "Not shy at all. Swim in open water despite plenty of hides available. Recognize people as food provider and swim to the front when people are present. Readily eat flake, tubifex, mosquito larva, etc... Didn't predate on nano fish such as Boraras, but did stress them out.", (94) Tanganyikafreak (k: 4), (95) Goodeid608, (96) booitsme3109, (97) angerygrover, (98) pointpleco (k: 2), who also notes: "Very cool looking fish if you can see it. Sits back in the plants a bit and likes a strong current as it loves to swim.".

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Breeding ReportsNone.
Article - Shane's World Reproduction Captive spawning of Glass Catfish
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Last Update2014 Nov 12 01:42 (species record created: 1997 Feb 01 11:22)

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