Kidney beans and most such legumes have very little fat of any kind. Peanuts and soybeans are exceptions to this, however.
One cup of cooked kidney beans contains just under a gram of fat (0.9 g). The USDA reports that there are 301 mg of Omega 3 fats, however. That's not a lot, but it's more than there is in 4 ounces of shrimp, which has about 200 mg. of Omega 3 fats. A serving of tuna, by comparison, has over 1,200 mg of Omega 3 fatty acids.
Thanks for writing,
Timothy S. Harlan M.D.