Fresh sliced cucumber, washed lettuce leaf, 'Zucchini', also spinach and sprouts but I tend not to use these as they break down quickly. Shelled peas (buy a bag of frozen peas pop a couple in some boiling water and wait till the cool down, pop out of shells and drop in plain view in tank.
My baby bristle noses actually ignore any green food I add, but this may be because I have aquite a bit of good algal growth...