Is there a proper ratio of DHA:EPA for adults and what is that natural ratio in fish?

The recommended intake for healthy adults from the American Dietetic Association and the Dietitians of Canada is 500 mg /day as DHA+EPA which theoretically could be all DHA or EPA or mixtures thereof. Since all fish contain both omega-3 fatty acids in different amounts and ratios, the 1999 Fatty Acid Workshop in Bethesda advised that at least 1/3rd of the target intake of DHA/EPA (650 mg /day in the case of the Workshop) should be represented by each of the omega-3 fatty acids. The average ratio (DHA:EPA) in the average fish as consumed in North America is approximately 2.4:1.