Behavioral changes in the goldfish, Carassius auratus, produced by treatment with nerve growth factor

Abstract

Goldfish were injected with a nerve growth factor which enlarges sympathetic and sensory ganglia. The behavior of experimental and control fish was then recorded on film by a movie camera mounted directly above an experimental chamber which had a grid on the bottom. As a result of injections of the nerve growth factor (NGF), fish showed increased activity, as measured by the distance covered and number of turns made in one minute of free swimming. These differences in activity were manifested when fish were in groups as well as when they were tested individually. Overall activity of control fish was much lower in groups than when isolated. This “group effect” was not seen to such a degree in the experimental fish. In response to fright, there was only a slight difference in activity of experimental fish as compared to control fish. Groups of control fish exhibited better schooling behavior than experimental fish, as measured by compactness of the group and parallel orientation of individuals. In response to a frightening stimulus, schools of experimental fish dispersed to a greater degree than control fish. Control fish, unlike experimental fish, regrouped within a few seconds of the disturbance. The decreased schooling behavior of NGF-treated fish can be attributed to their increased activity, caused by the increase in sensory and/or sympathetic innervation.