Akysis fontaneus is distinguished from congeners by a combination of the following characters: weakly emarginate caudal fin, convex dorsal surface of neurocranium making predorsal profile appear steeply sloping, presence of 4 large serrations on posterior edge of pectoral spine that are more than half width of spine, predorsal length 34.5% SL, pectoral-fin length 21.7% SL (not reaching pelvic-fin origin), length of adipose-fin base 18.7% SL and interorbital distance 42.3% HL (Ref. 80541).