There's another omega-3 fatty acid called alpha linoleic acid (ALA)—that's a plant-based omega-3 fatty acid, and even though people will turn to things like chia seeds or flax seeds to try and get that ALA, the conversion is remarkably poor. You could make an argument that you can get a decent amount from algae sources, like spirulina and chlorella, but they still don't touch the small cold water fish with a 10-foot pole when it comes to the actual availability of the omega-3 fatty acids.