they are rich in omega 3 and omega 6 if I remember right which helps in fat burning capabilities and basic neurological functions. Also they are high in vitamin A+D. Try not to buy the caps since fish oil is sensitive to heat and the caps are heat seal, hence not as effective as the pure oil in a opaque container.
P.S. it needs to be an opaque container since the oil is uv light sensitive, and also needs to be refrigerated.....