"Karl Townsend" fired this volley in
ews.com:

From what I've learned so far, it looks like someplace in a range of
100 to 600 volts does the job. I see the commercial unit is pulsed DC.
Apparently the field telephone is 100 volt hi frequncy AC.


Ideally, 90v @ 20hz. That's far from "hi frequncy AC".

We did some experimentation with various frequencies when I was diving
with SubArc in Florida in the '60s. (freshwater only) Some fish are
attracted by various frequencies up to low-audio. Some are repelled.
Almost none will voluntarily swim into stun range of a continuous signal.

Most seem best stunned by DC pulses or low-frequency AC. The range ain't
far. A fish that will be thoroughly stunned four feet from the
electrodes won't be fazed eight feet away (but will react to the shock by
going away from it). Apparently, they possess the ability to discern the
direction from which the shock is coming.

LLoyd