I regularly take fish oil having read a lot of material about its benefits over the years.
The New Scientist has an article this week that indicates that it might not be all it is cracked up to be.....Omega-3: Fishy claims for fish oil
Claim: fish oil supplements significantly improve reading, spelling and behaviour
Current thinking: a systematic review of all studies found insufficient evidence to identify any effect. The largest study to date reported no effect on cognitive function in later life
Then again, the New Scientist is notorious for supporting whatever is the Conventional Wisdom.