Hello, I was contacted by a friend about a shock he was getting at his biz that sells live fish and shrimp ? He stated it doesn't happen all the time so I told him to turn off the main breaker and see if it still happens . He did it does still shock him . Nothing extreme but how much does it take to kill baitfish and shrimp ? Then told him to contact the power company and they "checked" their side and said nothing was wrong . I also asked if it was at night in case a street light was the cause. I put a tester on the chain link fence around the tanks and got .5 volts. Any suggestions from those of you out there ? Thanks in advance.

Verify the grounding electrode system is working. Check connections, conductors etc. If in doubt drive new rods. If the water table is high it is probably salty and those rods might be corroded off just below grade. The "ground" from the PoCo is notoriously bad and you need a good, local, reference.

Thx for the reply . I didn't think with the main breaker off his grounding would be a concern ?

The stray voltage is probably coming in on the PoCo neutral. Ground at the PoCo is not always ground at the customer site. You can see enough ground shift to get a tingle voltage. A salt water tank would be the worst case. A few volts would wake you up.

So how do you convince the PoCo that it's their fault ?

You don't. They don't care
I did a survey of the pole grounds on my street after I saw about 3 amps on my service neutral. They ranged from less than an amp to about 3.
It is just a result of the wye distribution.

Thx Greg, as it turns out the grounding rod (galv) was only 4ft. long ! We replaced it with copper rod no more issues since . Thx. again.

No problem. That is why we are here. I always tend to look at the grounding first any time I see stray voltage or surge damage. It is the foundation we build the electrical system on.

Exactly. There will be always damages in grounding with stray voltage.