Melanorivulus proximus can be diagnosed from all other species of the M. pictus group except M. scalaris by having irregularly arranged, in­terconnected oblique red bars on flank, forming Y- and X-shaped marks. It differs from M. scalaris by the following characters: females with caudal fin base colour pale orangish pink (vs. pale yellow); males with dorsal and anal fin sharply pointed (vs. rounded to moder­ately pointed); origin of dorsal fin at vertical between base of 9th and 10th (vs. between base of 7th and 8th); 29-30 lon­gitudinal series of scales (vs. 31-34); pre-dorsal length longer in males (75.9-78.4 % SL vs. 73.0-75.0 % SL); anal-fin base longer (21.1-24.7 % SL in males and 18.8-21.4 % SL in females vs. 18.1-21.0 % SL in males and 16.2-18.5 % SL in females); and 9-10 infraorbital neuromasts around orbit (vs. 11-12) (Ref. 116860).