This is a little off topic for what you are trying to accomplish, but here is something I use.
I have signs that read
--
Warning - Toxic Algae Treatment in Progress
Consumption of fish and other aquatic life may result in serious illness or death.
Do not eat fish, turtles, frogs or other aquatic plants or animals from these waters.
No Swimming. No Fishing. DO NOT DRINK WATER.
--
Then I have the universal Biohazard logo printed at the bottom.
With our Vertex system pumping up bubbles and all the feeders around the pond, I think this has helped us keep would-be poachers at bay. I know I would never fish in a pond like this when I was younger (course, I was never a poacher either - so maybe my mind works differently).
Also - here in SC there are laws on what posted signs must say and how often they must be placed to hold up in court...perhaps your state has a similar law. If not a law, there may be a court precident or some administrative code that will give you the clarity you are looking for.
