If you consume enough cold water fish that are rich in Omega 3 fish oil to achieve levels even close to serious Omega 3 supplementation, you risk ingesting higher than safe levels of heavy metals and other toxins. Molecular distillation removes these toxins.

An anti-inflammatory diet can make up for the anti-inflammatory benefit of fish oil.

I just found an article that says pollock fish oil is lower in DHA in ratio to EPA whereas salmon based fish oil is higher in DHA in ratio to EPA. The DHA is the part that is more important for the brain. Look for high DHA content in the fish oil you buy. Anchovies appear to have the highest ratio of DHA to EPA.

Sports Research has 250mgs/687mgs DHA/EPA (36%) in 1250 mg softgel. VitaCost has 200mgs/400mgs DHA/EPA (50%) per 1200 mgs softgel
Brain Power + looks to have the highest ratio of DHA to EPA at 300mgs/400mgs DHA/EPA (75%) per 1500 mg softgel.
Amazon.com: Omega-3 Fish Oil | 15 mg Omega 3, 8 mg EPA, 6 mg DHA - Triple Strength Pharmaceutical Grade Liquid Softgel Capsules - No Fishy or Burpy Aftertaste - 18 Pill Count: Health & Personal Care
Brain Power + is confusing. They say Made in the USA then explain the anchovies are caught and processed in Chile then shipped to New Jersey where it is encapsulated.

Those fish oil softgels are a lot to swallow. 1200 to 1500 mgs. Awgh..