The relationship between fish oils and good cholesterol rate appears to be intimately bound together.
Indeed, epidemiological studies have found Greenland Eskimos, with diets rich in fish oil, are known to have greatly reduced cholesterol rate.
Fatty fish, like salmon, tuna fish, mackerel, sardine are advised for their richness in polyunsaturated fatty acids (PUFA's) omega-3 like EPA and DHA.