In terms of buying any kind of supplements, I would go GNC, they are tried and true. Also a really big brand that can be found almost anywhere on the planet. I am not 100% sure if they sell fish oils... Let me see...
What do you know... I didn't know they did.. Well they do
So I would get it from there, however, the best way is obviously just eat fish
I think it needs to be steamed though so to as not lose the vitamins/oils. Boiling it works, but only if you drink the water/or call it soup afterward.