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Akysis prashadi

Akysis prashadi
Prashad's Akysis
It can be differentiated from all other Akysis species by the following combination of characters: head length 20.6-23.8% of standard length (SL); head width 21.4-25.1% SL; caudal peduncle depth 7.7-9.8% SL; interorbital distance 35.0-37.0% of head length (HL); nasal barbel length 63.0-86.0% HL; absence of serrations on posterior margin of pectoral fin spine; caudal fin deeply emarginate with lower lobe slightly longer than upper. 

Members of the family Akysidae are often referred to collectively as 'Asian stream catfishes' since the majority are exclusive inhabitants of such environments. All have four pairs of barbels, and within this larger grouping Akysis species are diagnosable by possession of tuberculate skin and cryptic colour patterning typically comprising yellowish bands or blotches on a brownish background. 

Based on various morphological aspects the genus as originally considered was split into the A. variegatus and A. pseudobagarius species groups by Ng and Kottelat (1998), but all species of the latter group were reassigned to the genus Pseudobagarius by Ferraris (2007) on the basis of the following shared characters: tip of snout extends anterior to margin of lower jaw; mouth subterminal; narial openings (anterior and posterior nostrils) relatively large and closely-set; caudal fin deeply forked. Pseudobagarius spp. also tend to have a relatively extended body shape compared with Akysis, while in the latter the snout tip extends only slightly beyond the margin of the lower jaw, mouth orientation terminal to slightly subterminal, narial openings relatively small and widely-spaced and caudal fin truncate or emarginate. 

In recent phylogenetic analyses the family Akysidae has been grouped into an assemblage informally referred to as 'Big Asia' where it occupies a basal position and is most closely related to the families Amblycipitidae, Sisoridae and Erethistidae, these apparently forming a monophyletic group alongside the Bagridae and Horabagridae. The South American family Aspredinidae has often been affiliated with Akysidae in earlier studies, but is now considered more closely associated with the Doradidae and Auchenipteridae. 

All akysids possess venom apparatus at the base of the dorsal and pectoral spines and though not dangerous to a healthy human can inflict a painful sting, so should be handled with care when being removed from the water for any reason or during aquarium maintenance.