It has been proven that fish get stressed, however it hasn't been proven in studies whether they feel pain or not. We can only assume. That said, I wasn't saying that fish didn't feel pain, I just said they react to extreme cold different than mammals.
Thanks for the link, its really informative. I got some laughs out of the last animal listed with all the pets and livestock...rhinoceroses I noticed they didn't include birds.
Like all laws, including good ones, this one has its problems. There are many people, that are law abiding, that will not want to spend the time or money for the narcotics for their little fish. I think many people will just let the fish suffer and let nature take its course if there is no "simple" way. There is nothing in the article saying that one must take care of a sick fish. Yes, they could smush the fish, but many people can't muster enough guts to do it this way. Many people who know no fish husbandry buy fish, stick them all in a little tank with improper equipment, and the fish slowly die in their own excrement or die for one of the many diseases fish come with at aquarium stores.
I think Sweden would be better off spending their money and time educating the public on pet care than mircomanaging them. On the other hand, I have never been to Sweden and I don't know much on how their government functions. If our government tried to apply this law, it would not go over well.