Can you see me, or can you smell me? An investigation into information transfer in Betta splendens

Abstract

Visual communication in Betta splendens has been studied in great detail. Chemical information transfer in this species has been studied less, and the interaction between chemical and visual information transfer less still. Betta may have a need for chemical information transfer; a need which is often neglected when housing this species in isolation from conspecifics. There is evidence that many fish species communicate using visual signals and spy on one another using chemical cues. Which type of information transfer is important and how they interact in which social context is less clear. Eavesdropping and mate choice has been studied extensively in Betta, most often with visual signals being monitored. This study both aimed to find whether male Betta ‘wanted’ to be in receipt of conspecific chemical information, and to investigate the relationship between chemical and visual information transfer in social interactions between Betta of both sexes. Experiments using T-mazes concluded that male Betta did choose to be in receipt of conspecific chemical information when given the option. Experiments utilising mismatching multimodal information transfer concluded that female mating behaviour was significantly affected when given mismatching chemical and visual signals from males. Male agnostic and mating behaviour was not significantly affected. Historically females having witnessed an interaction between males have been shown to consistently choose the winner of the interaction over the loser. These findings suggest that chemical information transfer is important to female Betta in regard to sexual selection. This study as a whole informs us as to the importance of chemical information transfer in Betta. In males in terms of preference and choice, and in relation to dominant-subordinate relationships. In females in terms of eavesdropping and mate choice. It informs welfare and husbandry practices by suggesting that male Betta would prefer to be in receipt of conspecific chemical information, where they traditionally are kept in visual and chemical isolation from conspecifics. It also adds to our understanding of the role alternate modalities of information transfer play in the formation of dominance hierarchies and sexual selection.