A detailed morphometric study of populations of Raiamas salmolucius, previously considered widespread throughout the Congo basin, demonstrated that this species is restricted to the main course and right band affluents of the middle Congo basin. Two new species, previously confused with R. salmolucius, are described: R. marqueti from the Upper Congo including some affluents of Lake Tanganyika, and R. brachyrhabdotos from the Lower Congo and the Kasai basins. These three species differ from their Congo basin congeners by the following combination of characters: 42-48 scales in the lateral line; no spot on the caudal fin base; and the posterior border of the 4th infraorbital extending well beyond the posterior border of the 3rd. Raiamas salmolucius is distinguished from R. marqueti and R. brachyrhabdotos, by a longer head. Raiamas brachyrhabdotos is distinguished from R. marqueti by a deeper body, a longer pelvic fin, short and narrow predorsal mid-lateral black bars that do not extend to the lateral line and usually cover one to two rows of scales (vs. long and wide predorsal bars, extending below the lateral line and covering more than two rows of scales), and a convex predorsal profile (vs. a more or less horizontal profile). A key to the Raiamas species of the Congo basin is provided.