Frontiersman
Sharpshooter
Never heard that one. I would think it would still be better, maybe even filtering, for the fish. It can't be good to treat the water to kill cattails and then eat the fish.Be aware that cattails also will concentrate any heavy metals available in the soil, or so I've heard. I should check for a source on that info.
If it becomes a matter of daily survival, we might not care how much mercury is in the tuna.