Effects of social environment and personality on communication in male Siamese fighting fish in an artificial network

Individuals of the same species, sex, age and size may differ in suites of behaviour traits in a consistent manner across time and may thus represent different personalities. In a communication context, the personality of an individual may both affect and be affected by the behaviour of the individuals surrounding it within a network. We investigated the effects of a change of local social environment on two behavioural types, ‘persistent’ versus ‘sporadic’ signaller, in Siamese fighting fish, Betta splendens. Males visually interacted for 1 day in a communication network of seven fish in tanks arranged in a hexagonal grid, while we recorded space use and signalling data. We then exchanged the positions of two males with different behavioural types and observed them interacting the following day. ‘Persistent’ signallers were unaffected by the treatment, while ‘sporadic’ signallers increased the time spent in the inner front part of their tank, from which they could observe but not interact with the neighbours. Social instability (i.e. number of changed neighbours) raised the signalling levels of individuals independently of their behavioural types. We discuss the relationship between information gathering in a communication network and network composition in terms of behavioural types of its members.