The mechanisms that underlie the diversity of cichlids in the East African Great Lakes are poorly understood. Sexual selection through female choice based on male body coloration has often been suggested as a driving force behind the speciation of these fishes. The objectives of this study were to investigate, through mate choice trials, the cues that guide species-isolating female choice. In a group of sympatric Lake Malawi mbuna (rock-dwelling fish), we investigated both visual and chemical cues that might guide female choice by giving gravid females a choice between a heterospecific and a conspecific male. Visual cues, in contrast to olfactory cues, were sufficient to stimulate courtship and thus guide female choice of males. Furthermore, in contrast to other studies on related species, we found that females courted only with conspecifics even if color was not a cue. Species-isolating female choice is likely based primarily on visual information.