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of fish to current is maximum and approximately identical. A significant change
<br />in the sensitivity of fish to an electric current may be expected at a temperature
<br />of less than 5 and more than 27 - 30% when the physiological state of the fish
<br />changes sharply.
<br />Y CONCLUSIONS
<br />1. A dependence is established enabling the distortion factor of the electric
<br />field by the body of the fish to be determined. This reduces determination of
<br />the actual tension Ud of the fish body to calculation of the nominal tension of
<br />U1 and makes it possible to recommend Ud as one of the main criteria in assessing
<br />the effectiveness of the ad ion of an electric field on the fish.
<br />2. The dual nature of the action of an electric field (voltage and current)
<br />on fish, manifested in connection with thresholds of sensitivity and reactions
<br />%)n in relation to current density in the water is confirmed. This dependence
<br />is particularly strong when the electric conductance of the fish body and of the
<br />water is similar.
<br />3. It is shown that in uniform electric fields the threshold values of nom-
<br />inal body tension do not in practice depend on the length of the fish.
<br />4.11 When determining the thresholds of sensitivity and reactions the length
<br />of tlLraquarium should, in order to -avoid distortions in measurements, exceed the
<br />length of the fish by 5 times or more. If this condition is not fulfilled, it
<br />will be necessary to recalculate the value obtained according to formula (4).
<br />5. Between 10° and 25° the sensitivity of fish to an electric field is at
<br />its maximum and,_approximately identical. Differences in the threshold of sensi-
<br />tivity and reactions of fish within this temperature range are explained by the
<br />influence of temperature on electric conductance and current density in the water.
<br />Submitted March 27, 1979
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<br />150- l 151
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