Omega 3 fish oil? what is it good for? whats its benefits?

EPA: We all need two essential fatty acids in our diet but they have to be processed in the body to produce important metabolites that play a part in inflammation. Fish oil provides epa (eicosapentoic acid) that "dodges" the processing mechanism, thus providing a "ready made" metabolite that acts as an anti-inflammatory. This is very complex chemistry and is the simplest explanation that i can offer.