Just as a tangent... omega 9 is not essential for humans and the ideal ratio of omega-3omega-6 is 2:1 but the typical North American diet contain a ratio of 1:10-1:20. Yikes! Canola oil contains 9% omega-3 and 20% omega-6, while flax oil contains 57% and 14%, respectively. Most other commonly used cooking oils contain mostly omega 6 (which is we get so much) and many (e.g. safflower, sunflower, corn) do not contain any omega-3. Olive oil, contrary to popular belief, contain very little of omega-6 and no omega-3.
The best dietary sources of omega-3 are fatty fish, as they contain two types of omega-3 (DHA and EPA) which are much better absorbed by the body than the essential fatty acids from flax oil. There are risks associated with eating fish though, like high levels of bio-accumulating compounds found particularly in larger species. If you use fish oil capsules, speak to somebody knowledgeable an get a brand that is high grade to ensure toxins have been removed in the manufacturing process.
Flax seed oil and flax seeds (20% omega-3 and 5% omega-6) are also a good source, but like I said earlier, at least in humans, it is not as well absorbed by the body.