The information on omega-3 fatty acids can be overwhelming. Fish and fish oil are commonly thought to be the best sources. However, we can easily get enough omega-3 fatty acids as vegans, avoiding the cruelty and health hazards associated with consumption of fishes. Here are links to what three different vegan experts have to say on this:
The short answer is that if you are concerned about getting enough omega-3 fatty acids from your diet, you can take a plant-based supplement that is derived from algae.