If interesting in Omega-3 benefits, I would suggest watching this video with Dr. Rhonda Patrick and Dr. Bill Harris who has researched fatty acids for over 40 years. [1]
Haven't watched it, but I have some skepticism about both of them. Dr. Rhonda Patrick runs some "fitness courses" company, and Dr. Bill Harris is founder of OmegaQuant, which as I understand profits from Omega-3 tests.
Focussed on omega 3 from animal sources. ALA is the form in flaxseed and the like, and is explicitly called out as not addressed.
A reasonable point is made indirectly that eating fish may be better than taking supplements. I suspect in part it's because of oxidation and substitution in concentrate.
About eating fish, it may be just a correlation. People who eat seafood may have better lifestyle, or live in rich countries (The Netherlands, Japan, Norway, etc.)
Yea. There's lots of unknown unknowns. The NIH don't say they're useless and say some people see some benefits. There's the vitamin D side of things too. I live near the sea, I eat lots of fish. Deep Fried. I think it may not count as much..
[1] - https://www.youtube.com/watch?v=-f-CFQxaUY4 [video]