I know, this is way after your post. But what the hey...
I had gerbils.
For treats I gave them (every day or so, 1 or 2 of these) : Wheat Thins, saltines & Ritz Crackers - Thin carrot sticks - fresh apple slices - whole seedless grapes (it was great fun to watch them figure them out) - a little sliced fresh peaches - the occasional whole peanut, hazelnut, or walnut (it kept them busy for awhile) - Gerbil/hamster waffle-pattern wafers (they're green & beige) - Cheerios (plain) - raisins.
Always clean the uneaten fresh food out at the end of the day.
"That house is doubly blest / Which to our feline friends gives rest." (The Black Cat, 1941 movie)