I've been asked a few questions about fish because as you all know I'm a big fisherman and I eat the fish I catch typically. So heres a few pointers for all of you when buying fish or catching them.

Store bought

Farm Raised:
This is a total waste of your money. The farm raised Salmon will not have the fatty acids in them. They are raised in a pond that typically experiences runoff from cattle waste etc. Very high pollutants in this poind. They are fed what is the equivalent of dog food pellets with hormones to make them grow. The fatty acids come from the Salmon being in a wild environment feeding on the smaller fish that contain large concentrations of these fats.
The same holds true for farm raised catfish. Only catfish are not as well known for the omega 3.

Freshness '
As a general rule if it smells fishy don't buy it. Fresh fish will not smell like fish.

Wild fish: Whether you catch them or get them at a market

Look for the smaller fish. They taste better and have not spent years in the water building up all the pollutants i.e mercury, dioxins, pcb's. The larger fish are usually 10-20 years old and have been exposed to all that mercury etc and have very large fat stores where these toxins will accumulate. With the execption of MOST Salmon species as they only live 5 years before they spawn and die. 2 Salmon species do not die. Atlantic and Kokanee (pink)

I know that Salmon and trout are much revered for their Omega 3 but understand that ANY fish thats primary diet is smaller fish will contain high levels of Omega 3. Basically any pelagic (open water roaming) fish species will be Omega 3 rich.

I posted this because some have expressed concerns about eating fish and the toxins in the waters. The benefits of eating these protein rich treats far outweigh the risks of any toxins. The above will help you minimize your exposure to such waterborne chemicals. This is mostly freshwater of course since I don't live near an ocean. But the same general rules could be applied to ocean fish.

I always hear that "fresh fish doesn't have a smell". Maybe I'm just hyper-sensitive to it or something, but I've never never experienced that. It always smells fishy to me. There's a fairly famous international market near me, they fly in fresh fish and they even have their own fish hatchery and their stuff smells fishy to me. I typically have to force it down if I eat fish. I tried swordfish once and literally vomited...although I occasionally enjoy a nice piece of salmon

The larger the fish, the more toxins like mercury it will have. As you said, farmed fish are not as good.

If you want to get more omega 3 (which i think everyone should!), then get some fish oil supplements and take at least 1gram of DHA and EPA

I agree but matt182, this is a turnaround on your part since you have always claimed one should only eat a balanced diet without supps.

Not many polluted waters where I live I generally catch kahawai and gurnard and sometimes snapper.

Fish oils are the general exception

And yes, i'm sure there are some nice fish in New Zeeeeeland