This is weird and sort of disturbing. The Fish List was a project among the various organizations who had been keeping lists of environmentally less stupid fish to buy and eat. The Monterey Bay Aquarium, a couple of environmental groups, and a seafood industry group had managed to cooperate enough to make a good list of which fish were more reasonable to eat and healthier. I can only assume the alliance collapsed for some reason. So now we have competing fish lists. The ones I’d seen recommended as pretty authoritative before have differing objectives.
For now I’d recommend the Monterey Bay Aquarium’s Seafood Watch which has lots of good info and also little downloadable cards in .pdf so that you can know what you’re doing when buying and eating.