I know I'm replying TEN years later, but... I have had the same exact problem. I cooked snapper a hundred times and it was delicious, then suddenly, every time I tried it, I got a curled piece of rubber. We call it "boot fish" (tough like a boot.. I have tried grilling it, blackening it, baking, pan frying, with skin, without skin, and the list goes on and on. I would buy mine from HEB in the fish case previously frozen, same as I always did. I asked them if their distributor changed but they were not sure. I haven't bought snapper for years until today from Central Market and I'm hoping I don't get those results. I am sure I am not overcooking it or using a bad technique because I cooked it sooooo many times successfully before this started. I am convinced it's not real snapper. Good luck!