Make sure you use treated/refined oil that had all pollutants removed.

Their are many benefits and it is an essential source of omega 3. This is actually an advantage that fish oil of good quality has over simply adding fish to your diet that can't really be refined and have their pollutants extracted. Another minor side effect is that some people have a "fishy aftertaste" after taking their fish oil pills. Basically you might burp with a breath similar to if you just ate fish. Some of the Fish oil side effects are that, like the fish they can originate from, contain pollutants.

A lot of research is backing up Alzheimer patients being studied with fish oil supplements ( specifically the omega 3 contained in the supplements) and how it might improve or prevent their condition.

Other benefits are how it helps your heart and skin condition. One of the reasons to eat it is research has shown that it helps your brain stay healthy.

Theirs a lot of vitamins and supplements out there and one of the most important and recently popularized one is fish oil.