Kryptopterus cryptopterus

Kryptopterus: from the Greek kryptos, meaning 'hidden', and pterýgio, meaning 'fin', in reference to the reduced or absent dorsal-fin in members of this genus.

cryptopterus: from the Greek kryptos, meaning 'hidden', and pterýgio, meaning 'fin', in reference to the reduced or absent dorsal-fin.

Known from the Malay Peninsula and Singapore plus Greater Sunda Islands of Sumatra, Borneo and Java with populati0ns from Thailand, Cambodia, Laos and Vietnam which had formerly been considered conspecific now referred to K. geminus (Ng, 2003)[5].

Type locality is given as 'Bandjarmassing' which corresponds to a town now more commonly referred to as 'Banjarmasin' in South Kalimantan (Kalimantan Selatan) province, Indonesia (Borneo).

Inhabits flowing rivers and larger streams typified by turbid water with a lot of suspended sediment.

An aquarium with base dimensions of 120 ∗ 45 cm48 ∗ 18 in or equivalent should be the smallest considered.

Décor is relatively unimportant although this species prefers weakly-lit conditions and may become skittish in the absence of cover.

Do not add introduce it to a biologically immature aquarium as it can be susceptible to swings in water chemistry.

Probably a predator feeding on crustaceans, invertebrates and smaller fishes in nature, although there should be no need to use such live foods in captivity.

Offer a varied diet comprising sinking dried foods, live and frozen bloodworm, Tubifex, etc., and perhaps the occasional small earthworm.

Generally peaceful though it may predate on smaller fishes and is somewhat timid so does not compete well with much larger, robust or otherwise boisterous species.

Peaceful, comparably-sized cyprinids, loaches and other catfishes perhaps constitute the best options but be sure to research your choices thoroughly prior to purchase.

K. cryptopterus is gregarious and tends to form schools so ideally four or more specimens should be purchased.

Adult males are noticeably slimmer than females but additional information is contradictory with some sources stating that the posterior edge of the pectoral-fin spine is serrated in males (vs. smooth in females) and others that there is no such difference.

Unrecorded. In nature the closely-related congener K. geminus (see 'Notes') spawns at the onset of the wet season with young specimens common in seasonally-inundated areas.

This species is sometimes traded as 'smokey glass catfish'.

Its closest relative is K. geminus, populations of which were formerly considered to represent K. cryptopterus, and these two can be distinguished from congeners by the dorsal profile lacking a nuchal concavity (vs. possessing a nuchal concavity) and possessing short maxillary barbels (extending to the pectoral-fin base vs. extending beyond tip of pectoral-fin).

K. cryptopterus can be distinguished from K. geminus by possessing a wider head (12.2-14.2 % SL vs. 9.5–12.0), shorter anal-fin (57.2-62.9 % SL vs. 62.2–72.7) and snout (35.1-39.8 % HL vs. 39.5–45.3), and less laterally-placed eyes (ventral two-thirds of the orbital margin visible when the head is viewed ventrally vs. only the ventral half).

K. cryptopterus and K. geminus can be further told apart from all other silurid catfishes by possession of an anteriorly truncated supralabial fold with the lower edge extending beyond the base of the maxillary barbel and an elongate antorbital process of the lateral ethmoid that is not anteroposteriorly compressed.

Kryptopterus species are found only in Southeast Asia and the genus has been considered polyphyletic since Bornbusch (1995) with some former species already moved to the genera Phalacronotus and Micronema.

Those still contained within the genus are assigned to a number of putative species groups as follows:

K. bicirrhis group: K. bicirrhis, K. lais, K. palembangensis, K. macrocephalus, K. minor, K. piperatus, K. vitreolus
K. cryptopterus group: K. cryptopterus, K. geminus
K. limpok group: K. limpok, K. mononema, K. dissitus, K. baramensis, K. hesperius
K. schilbeides group: K. schilbeides, K. paraschilbeides

Bombusch (1995) identified the K. bicirrhis group as a distinct clade although he didn't propose any synapomorphy to diagnose it.

Ng and Kottelat (2013)[10] later noted that members normally have fewer anal-fin rays (46–67 vs. 64–85) than other congeners and placed K. piperatus and K. vitreolus within the group based on this character.