Diagnosis: Distichodus kasaiensis is distinguished from D. affinis, D. altus, D. decemmaculatus, D. noboli, D. notospilus and D. teugelsi by the higher number of lateral line scales, 57-65 vs. 37-46; from D. antonii by the inferior mouth vs. terminal, the higher number of dorsal-fin rays, 27-29 vs. 21-25, and the lower number of dark vertical bars, 6-8 vs. 9-14; from D. fasciolatus by the higher number of dorsal-fin rays, 27-29 vs. 24-26, and the lower number of dark vertical bars, 6-8 vs. 13-20; from D. langi by the lower number of lateral line scales, 57-65 vs. 68-70, and the lower number of vertical bars, 6-8 vs. 13; from D. lusosso by the inferior mouth vs. terminal, and the short snout vs. elongated; from D. maculatus by the absence of dark blotches all over the body; and from D. sexfasciatus by the higher number of dorsal-fin rays, 27-29 vs. 24-25, the higher number of teeth in the outer row of the upper and lower jaw, 15-25 and 16-26 vs. 12-14 on both jaws, and the greenish body colouration vs. orange-reddish (Ref. 122092). It is distinguished from its most similar species D. atroventralis by having more dorsal-fin rays, 27-29 vs. 22-24, fewer teeth on the upper jaw, 15-25 vs. 18-36 (overlap due to positive allometry), and a longer dorsal-fin base, 24.9-33.7% of standard length vs. 20.1-28.8% (overlap due to positive allometry); and from D. ingae by having fewer lateral line scales, 57-65 vs. 69-73, more dorsal-fin rays, 27-29 vs. 26, and a smaller prepectoral distance, 21.4-30.0% of standard length vs. 29.1-30.2% (overlap due to negative allometry) (Ref. 122092).

Description: body elongated and laterally compressed; dorsal profile straight from tip of snout to above posterior border of eye, then convex to end of dorsal-fin base, straight between dorsal and adipose fins, and concave between adipose and caudal fins; ventral profile straight from tip of snout to level of posterior eye border, concave afterwards until end of anal-fin base, and convex between latter and caudal fin (Ref. 122092). Mouth inferior (Ref. 122092). Caudal peduncle deeper or equal to its length (Ref. 122092). Dorsal fin with a high number of rays and a straight to slightly convex distal margin; dorsal fin origin well in front of pelvic-fin origin; adipose fin at equal distance from dorsal and caudal fins; only proximal two-thirds of adipose fin scaled; anal fin with a concave distal margin; length of pectoral- and pelvic-fin rays decreasing from last unbranched ray to last branched ray; distal tip of pectoral fin reaching, or almost reaching vertical through dorsal-fin origin; pelvic fin always reaching anterior border of vent, sometimes even beyond; caudal fin forked; lobes generally pointed although sometimes more rounded; upper lobe slightly longer than lower lobe; caudal fin, except for its posteriormost fifth, almost entirely covered with small scales (Ref. 122092).

Colouration: In preserved specimens, overall body colour light brown-yellowish with lighter belly; six to eight continuous blackish vertical bars on flanks; whether vertical blackish bars disappear in larger specimens is unknown; distinct black spot in middle of caudal peduncle; dorsal fin with whitish-greyish rays connected with translucent membranes, with scattered small, blackish melanophores of irregular size; proximal two thirds of adipose fin with same colour as body, distal third translucent, often with very thin, blackish distal margin; pelvic fin blackish; pectoral fin whitish at base, more translucent distally; anal fin whitish; caudal fin greyish to light brown (Ref. 122092). In life, overall body colour greyish green, belly yellowish white; pelvic fin dark brownish orange, but not as dark as in preserved specimens; anal fin greyish at its base and somewhat darker distally; caudal fin with three transversal bands with different shades of grey, becoming paler from proximal to distal edge; otherwise, colour pattern similar to that of preserved specimens (Ref. 122092).