DETERMINATION OF THRESHOLD CURRENT DENSITIES FOR DIFFERENT REACTION OF FISHES USING A PANTOSTST

Abstract

The threshold current densities required for first reaction,
galvanotaxis and galvanonarcosis of fish depended upon species,
length of the body. conductivity of water, nature of current and
frequency of impulses. The threshold values and their ratios
decreased with increase in length of fish. With rise in conductivity
of water in . the ratio of 1:4:13, these values increased in
the ratio 1 : 2 :-5; -Impulse D. C was superior to continuous D. C
and the threshold values of current densities for different reactions of
fish decreased with rise in impulse frequency reaching minimum at
an impulse frequency of 48/sec. Among Safmo irideus, ldus melanotus
and Cyprinus carpio, the first one was affected earlier and required
minimum current densities to exhibit the reactions, while the last
one showed similar reactions only at higher current densities.