Singing above the chorus: cooperative Princess cichlid fish (Neolamprologus pulcher) has high pitch

Abstract

Teleost fishes not only communicate with well-known visual cues, but also olfactory and acoustic signals. Communicating with sound has advantages, as signals propagate fast, omnidirectionally, around obstacles, and over long distances. Heterogeneous environments might favour multimodal communication, especially in socially complex species, as combination of modalities strengths helps overcome their individual limitations. Cichlid fishes are known to be vocal, but a recent report suggests that this is not the case for the socially complex Princess cichlid Neolamprologus pulcher from Lake Tanganyika. Here we further investigated acoustic communication in this species. Wild and captive N. pulcher produced high frequency sounds (mean: 12 kHz), when stimulated by mirror images. In laboratory experiments, N. pulcher produced distinct two-pulsed calls mostly, but not exclusively, associated with agonistic displays. Our results suggest that male N. pulcher produce more sounds at greater durations than females. Thus, we confirm that the Princess cichlid does not produce low frequency sounds, but does produce high frequency sounds, both in combination with and independent from visual displays, suggesting that sounds are not a by-product of displays. Further studies on the hearing abilities of N. pulcher are needed to clarify if the high-frequency sounds are used in intra-or inter-specific communication.