Let me help you out. Flax seed and fish fat are both Omega-3 oils. Walnuts also contain Omega-3 fat.
Land Omega-3 fat (ex. flax, and walnuts) are (LNA) Alpha-linolenic acid. Once LNA is taken into the body, they convert in small quantities to (EPH) Eicosapentaenoic acid and (DHA) Docosahexaenoic acid. Remember, I said in small quantities.
Water Omega-3 fat (ex. salmon, tuna) are already EPH/DHA. The body does not have to convert it. This makes it an efficient form of Omega-3. Water Omega-3 fat are also "eicosanoids". All you have to remember about eicosanoids are they are "natural" inflammation reducers. That means they could reduce aches and pains especially in the joints (A big bonus). In addition it may reduce cholesterol.
1) Fish is superior to Flax.
2) Salmon is your best choice as it contains the most Omega-3 content.
3) Real fish is a better way to get Omega-3 than a pill (plus all the extra protein).
A common side affect to fish oil capsules is that you may burp and it could leave a slight taste in your mouth (A minor set back considering the benifits). I have found a fish oil capsule with absolutely no bad taste. At GNC, they have fish body oils 1000. They are simply great. I got a good deal because the 2nd one was half off. I hope this helps. (Shawn).