Is Boldness in Climbing Perch (Anabas testudineus) Sensitive to the Apparatus Used for Measurement?

Swimway and open field are the two popular apparatus used for measuring boldness - the propensity to take risky decisions - in various piscine species. The present study compared boldness exhibited by an air breathing freshwater fish climbing perch in a swimway, rectangular open field, intermediate stages between these two apparatus and circular open field. Impact of the modification of the start chamber by providing substratum made up of cobbles and covering the water surface using water plant hydrilla, alone and in combinations on the boldness was also tested. Our results revealed that the apparatus has a significant impact on the boldness in climbing perch. The presence of a shelter in the experimental arena (swimway) and cobble substratum in the start chamber of the apparatus were found to be reducing boldness in this fish, while hydrilla cover on the water surface neutralised the impact of cobble substratum. Repeated exposure and resultant familiarity with the arena increased boldness of climbing perch but the pattern of modification of this behavioural trait exhibited during the course of experiment was divergent across the instruments. These results point towards the need for critically analyzing the influence of instruments used for measuring various behavioural traits and considering biological needs of the subject species while designing the apparatus.