Lateralization of response to social stimuli in fishes: A comparison between different methods and species

We measured the time spent in monocular viewing during inspection of their own mirror images in females of three species of fish (Xenotoca eiseni, Gam busia holbrooki and Xenopoecilus sarasinorum) using a rectangular tank in w hich animals could observe their own reflections in two mirrors positioned along the major walls, and in females of five species of fish (X. eiseni, G . holbrooki, X sarasinorum, Danio rerio and Gnatonemus petersii) using a qu asi-circular tank in which fish could rotate clockwise or anticlockwise and observe their own reflections in a mirror positioned along the outer wall. Results revealed a consistent left-eye preference during initial sustained fixation in all species irrespective of the apparatus. However, in the qua si-circular tank, fish showed more variability of response. The asymmetry w as apparent during the first 5 min of observation and tended to fade therea fter, probably as a result of habituation. These findings add to current ev idence for a quite invariant pattern in the direction of lateralization in similar tasks in a variety of vertebrate species, with a preferential invol vement of structures located to the right side of the brain in response to the viewing of images of conspecifics. (C) 2001 Elsevier Science Inc. All r ights reserved.