In Malawi cichlids of the Pseudotropheus complex, acoustic signals have been shown to act on females during inter-specific mate recognition and, together with visual and chemical cues, may thus play a role in the fast adaptive radiation of African cichlids. The aim of our study was to investigate the role of the acoustic channel in an agonistic context. We recorded emitted sounds and associated behaviours during interactions between a resident and an intruder in both sexes of Pseudotropheus zebra. To assess the importance of sound communication, fish were allowed to interact only via acoustic channel (playback experiment), only via visual channel, or via both channels. The fine acoustic structure of recorded sounds was analyzed in both temporal and frequency domains. First results bring new information on sound structure and show that behaviour-related and/or individual-related information could be coded by the emitted sounds.