Effects of Daily Forced Exercise on Anxiety of Zebrafish (Danio rerio) Living in Impoverished Environments

The purpose of this research was to investigate the effects of forced exercise on anxiogenic behavior in Danio rerio living in different environmental conditions. To study this relationship, zebrafish were introduced to the following housing environments for several weeks. Fish in Group 1 were exposed to brown gravel and green, plastic plants (enriched environment), and fish in Group 2 were exposed to no brown gravel and no green, plastic plants (impoverished, structurally-barren environment). Fish from both housing environments were randomly assigned to be exposed to exercise or no exercise (control). Fish in the exercise group were forced to swim against a current generated by a submersible water pump daily. Fish that were in the non-exercised group were treated in an identical manner each day, but the water pump was off (controlling for the effects of stress related to the procedure). The light/dark and novel tank tests were used to measure anxiety-like behaviors. It was hypothesized that subjects exposed to daily forced exercise would be protected from the adverse effects of living in a deprived environment. Results indicated a significant main effect of exercise only for the number of entries into the top portion of the novel tank, which suggests a decrease in anxiety. All other behavioral measures of anxiety were not significant