I have been on fish oil for about 3 months and notice no difference in the UC. However, I agree with other posts that fish oil has wide ranging benefits so might as well keep taking it.
I tried many varieties and also could not STAND the fish burps, the best I have found so far is Carlson's Cod Liver Oil (recommended to take the kind w/vitamin D during the winter). There is still some fishiness when burping for a few hours but nothing like taking the capsules. I found it at my local health food store, but here is the product:
http://www.carlsonlabs.com/p-107-cod-liver-oil-lemon-flavor.aspx
Really not bad at all if you mix it with a little juice and shoot it back,,,I can even tolerate taking it by the spoonful and drinking juice afterwards. Good luck!