The Role of Visual and Chemosensory Signals in Male–Male Aggression of the Cichlid <i>Astatotilapia burtoni</i>

Sensory processing of communication stimuli is essential for the survival of organisms across all evolutionary branches. Multimodal signaling, the use of multiple sensory systems is crucial in this process, but little is known about the relative importance of different senses used during aggression. We used the African cichlid fish, Astatotilapia burtoni, to test how visual and chemosensory signals in male-male interactions influence behavior. Males of this species exist in a dominance hierarchy, where brightly colored dominant individuals aggressively defend territories for reproductive activities. Focal males were presented with visual and chemosensory signals from other males either alone (unimodal) or together (bimodal). We found that vision is necessary for males to engage in aggressive behaviors such as frontal displays, lateral displays, and border fights. While chemical signals alone did not evoke aggressive behaviors, we find slight reductions of some aggressive behaviors when bimodal stimuli are provided. This study is the first to examine how visual-chemosensory signaling impacts male-male aggressive behavior in A. burtoni and provides insight on how these signaling modalities mediate territorial interactions.