The behaviour of stressed fish

Fish are widely used as pets, in agriculture, and increasingly in scientific research. It is important to be able to test whether particular husbandry practices are stressful for them and, if so, whether changes to such practices are effective in enhancing welfare. Animal welfare researchers have developed a test that capitalises on two features of the behaviour of stressed fish – their tendency to avoid light coloured areas (scototaxis) and their tendency to swim to the bottom. The ‘scototaxis-diving’ test involves placing fish such as stickleback into a tank divided into two halves, one coloured black and the other white, separated by a divider with a gap through which the fish can swim. The time that fish choose to spend at the bottom of the tank and on the black side may be a useful indicator of how stressed or ‘anxious’ they are.

This research was published in Behavioural Brain Science by Ralph Thompson, Liz Paul, Andy Radford, Julia Purser and Mike Mendl. The paper can be viewed here