Galaxias fuscus is distinguished from all its congeners within the Galaxias olidus complex by a combination of the following characters: overall color ranging from dull to moderately bright orange, yellow-orange to reddish orange; body pattern generally absent except sides of trunk with a series of large, distinctive, dark bars surrounded by halos present, generally centered on the lateral line, relatively widely spaced and extending from above the pectoral fin base to above the pelvic fin base, very rarely faint blotches also on dorsal surface; dorsal surface of trunk broadly flattened anteriorly from above pelvic fin bases; caudal peduncle very deep (7.2-10.4 % SL); long caudal fin (12.1-19.2 % SL), much longer than caudal peduncle; long anal fin (14.2-18.6 % SL); large pectoral and pelvic fins (11.4-17.6 and 9.5-16.2 % SL, respectively); pelvic fins set far back (prepelvic length 53.4 % SL); large bulbous head, length 21.0-26.7 % SL and longer than pelvic fin to anal fin length, relatively wide and deep (56.7-75.6 and 35.5-53.3 % HL); nostrils short, not visible from ventral view; mouth large, with long upper and lower jaws (33.9-46.7 and 30.2-43.6 % HL respectively) and wide gape (34.3-53.9 % HL); most posterior extent of mouth about 0.8 ED below ventral margin of eye; 0-1 pyloric caecae, short (1.0 % SL) when present; and anal fin origin usually under 0.78 distance posteriorly along dorsal fin base (Ref. 98815).