Escape behaviour elicited by a visual stimulus. A comparison between lateralised and non-lateralised female topminnows.

Studies over the past 30 years suggest that functional lateralisation occurs in many animal species. Preferential eye use is ubiquitous among fish, and recently some advantages of being lateralised have been reported in the golden topminnow, Girardinus falcatus, using fish from lines selected for high or low degrees of behavioural lateralisation. In the present paper we investigated whether non-lateralised fish differed from lateralised fish in escape behaviour elicited by a potentially dangerous stimulus. A total of 56 female topminnows were observed when swimming in an unknown environment in which the shape of a predator was presented on either the right or the left side of the visual field. We found no side differences in latency and efficiency of escape reaction and on the whole non-lateralised fish escaped as quickly as lateralised individuals. We discuss our results in the light of recent findings suggesting that the development of lateralisation in the fast escape response in fish may be controlled by a mechanism distinct from that controlling the asymmetric placement of most other cognitive functions.