Factors Controlling the Input of Electrical Energy into a Fish (Cyprinus carpio L.) in an Electrical Field1

The presence of a fish distorts the electrical field established initially in the water. This distortion, which changes the voltage gradient affecting the fish, and hence the electrical energy-input, is dependent upon the resistivity of the fish as compared to that of the surrounding water. These resistivities depend upon the temperature and chemical content of both water and fish. The criterion of electrical energy-input into the fish may be more important than voltage gradient in the water as an index to fish reactions to electrical fields. A method of measuring fish resistivity is described, and the results of an investigation of the effects of temperature and resistivity on water-to-fish resistivity ratio is presented. The idea is discussed that variation of these conditions may cause changes in energy-input to the fish by factors of ten or twenty even though voltage gradient in the fish-free water remains constant.