Xenocharax crassus Pellegrin, 1900, originally described from the Alima River (Congo basin, Republic of Congo) but synonymised with X. spilurus by Daget in 1960, is rehabilitated. Xenocharax crassus, a Congo basin endemic, is distinguished from X. spilurus, the latter found exclusively in basins of the Lower Guinean ichthyofaunal province, by the presence of a large black mark on the anterior part of the dorsal fin (versus absence), a small, round, black spot at the base of the caudal peduncle (versus a large ovoid spot covering the peduncle base), and a wider mouth (29-34 % HL vs. 24-29). For specimens of similar sizes, X. crassus has a shorter dorsal-adipose distance than X. spilurus. Furthermore, most X. crassus specimens have 6 supraneurals (frequency: 83 %) versus 7 (frequency: 79 %) in X. spilurus. With molecular data the species is readily distinguished from X. spilurus by 10 apomorphic, non-synonymous nucleotide transitions in the three sampled genetic markers (nd2, cyt-b, and myh6). A lectotype is designated for X. spilurus.