Recently, specimens belonging to the genus Haplochromis have been found in the Ituri River (Congo basin). They clearly do not belong to any of the species known from the Congo basin, but strongly resemble H . aeneocolor from the Lake Edward/George system. We examined whether this population represents a new species or is conspecific with H . aeneocolor. A morphological comparative study was executed based on 11 counts and 23 measurements on 64 specimens. The results revealed the Ituri specimens to differ from the types of H . aeneocolor in snout length, premaxillary pedicel length and eye diameter. Since these few differences are correlated, and head morphology is known to be subject to adaptive responses in haplochromine cichlids, they were considered the result of morphological adaptation to a riverine habitat rather than an indication of heterospecificity. Probably, H . aeneocolor has accidentally been introduced into the Ituri region together with tilapias used in aquaculture, and has subsequently established a stable population in a riverine environment. As fish introductions can have a severe impact on aquatic ecosystems, improving our knowledge as well as a good management of aquacultural activities is essential.