I've been a big fish eater my whole life........
Fish never gave me the runs, but how you prepare the fish....or what you eat along with the fish might....
You may want to investigate .. ..
I also love aLOT of veggies with my meals, certain veggies, when eaten in abundance.....have me pukin' out the back door -
you probably have a stomach bug, or drank too much RedBull with the fish.
