I'm not sure if thats the stuff they put in the fish pills, it might be, because the benefits seem to be the same:
http://en.wikipedia.org/wiki/Cod_liver_oilCod liver oil is derived from cod livers. It is a nutritional supplement, in the past commonly given to children. Cod liver oil is one of the most effective providers of omega-3 fatty acids, and an excellent source of vitamin A and vitamin D. It is widely taken to ease the pain and joint stiffness associated with arthritis[1] but has also been clinically proven to have a positive effect on heart,[2][3] bone,[4] and brain[5] health, as well as helping to nourish skin,[6] hair, and nails.