Abstract
Locomotor behavior of goldfish (Carassius auratus) and green sunfish (Lepomis cyanellus) was recorded automatically in a 5x5x0.5 m monitor tank before and after treatment with thyroxine. The fish were treated either in a 0.4 ppm solution of thyroxine or by implanting thyroxine-cholesterol pellets into the body cavity. In goldfish, contrary to available literature, the amount of distance traveled per hour was lower after treatment. Similar changes occurred in a number of other related aspects of locomotion except for the velocities of the goldfish which increased after treatment. The green sunfish, on the other hand, showed both increased velocities and increased distances traveled per hour after treatment. The spatial distributions of these changes in the monitor tank were discussed in relation to the patterns of water flow. The goldfish were found to slow down when the flow was turned off and the thyroxine treatment was found to enhance this effect. The response of the green sunfish to water flow was in the opposite direction. A similar increase in the goldfish to shallow salinity gradients was described. Through such mechanisms, seasonal displacements of fish populations may, in part, result from cycles of thyroid activity.
Westlake, Garson Frederick (1973). Some effects of thyroxine on locomotor behavior in fish. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -158454.