I don't agree that taking omega 3 (or 6 or 9) is a fad. All the oils most of the population consumes today have been refined and hydrogenated to lengthen shelf life - thereby reducing the "good fats" found in them.
Our diets today are really lacking in omega 3s and 6s. More so 3s I think. These good fats support our heart, and a healthy immune system. They are important for eye health. These good fats also insulate nerve fibres and are the building blocks of hormones and transporting nutrients. They are important structural components of all cell membranes - so i'd think they are fairly important in one's diet. If you're not getting them from the food you eat - supplementing is a great idea I would think - I take them every day.
I would like to warn you, though, to look for fish oil that is contaminant free. Some can contain mercury, heavy metals, pcbs and pesticides. I take usana's biomega-3 - which is 99.99% free of all of these).
Good luck. Stay healthy.