K. vitreolus is well-known to aquarists but has been misidentified for at least 80 years. © Unimati.dk

Over the last few decades the aquarium glass catfish has generally been referred to as Kryptopterus bicirrhis or, more recently, K. minor in both aquarium and scientific literature, but a new paper by Drs. Heok Hee Ng and Maurice Kottelat reveals that this popular species has in fact been misidentified for over eighty years.

The fish is native to rivers of peninsular and southeastern Thailand and the study, published in the journal ‘Zootaxa’ this week, demonstrates it to be a previously unnamed taxon now formally named Kryptopterus vitreolus.

It’s been known in the aquarium hobby since at least 1934 and is enduringly popular due to its transparent appearance, though its identity has never been fully-investigated.

K. vitreolus continues to be a popular aquarium fish. © Håkon Haraldseide

K. vitreolus can be distinguished from congeners by the following combination of characters: body transparent in life; maxillary barbels reaching beyond the base of the first anal-fin ray; dorsal profile with a pronounced nuchal concavity; snout length 29–35% head length (HL); eye  diameter 28–34% HL; body slender (depth at anus 16–20% standard length (SL)); caudal peduncle slender (depth 4–7% SL);  14–18 rakers on the first gill arch; 48–55 anal-fin rays.

Its specific name is derived from the Latin vitreus, meaning ‘of glass’, in reference to its transparent appearance in life.

The authors also draw attention to the fact that this species appears never to have been bred on a commercial basis, and that its status in the wild requires investigation since it’s collected intensively for the aquarium trade and has a relatively restricted range.

For further information please refer to the full paper (link to abstract only): Ng, H-H, and M. Kottelat. 2013. After eighty years of misidentification, a name for the glass catfish (Teleostei: Siluridae). Zootaxa 3630(2): 308-316