It doesnt take much in toxic metals in parts per million to make fish inedible. Even fancy albacore tuna which apparently absorbs mercury more readily than regular tuna is not supposed to be consumed at all by pregnant women and sparingly by others.
Yep, always make sure, for those of you who do a lot of fishing, to know where the fish you are catching ( and eating ) are coming from. The fish are surrounded by the toxins their whole life so it becomes encorporated in them through out their whole body. Those toxins are then transferred to you when you eat them. Your local F&G should have lists and/or maps of where it is safe to eat the fish you catch and where it isn't safe.