Is salmon the only good fish?

It seems no matter what ailment one is seeking to cure through diet, like obesity, diabetes, high blood pressure, pain, etc. there is one food that always seems to be mentioned and that is salmon.  I can eat it if I have too but there has to be some other fish out there that has a good taste that is healthy too.  Maybe it isn't as healthy as salmon but milder.  I've read some negative things about salmon too.

When I started working in a grocery store seafood departments were unheard of  but when they were finally accepted it seems the only fish we could sale was catfish, flounder and croakers.  We sold lots of shrimp and crablegs and some perch but not much of anything else.  It took a lot of work to get people to try other fish.  Steak fish like salmon, halibut, mackerel, shark, and tuna were occasional sells but the bread and butter of the seafood department was catfish, croakers, shrimp, and crablegs. 
Now it seems if a seafood department is out of salmon they are out of business.