is this diet OK?

[Kathleen]

Hi.  I am 53 years old and rather new to gerbils.  I have 2 sisters I got from a local pet store with a very good reputation.  They are black with white stripes running from their chin to about the level of their front legs.  One also has 3 white toes.  Are they black spotted?   My real question is their diet.  They were about 5 or 6 weeks old when I got them , and had been eating a seed, grain, and pellet gerbil mixture from the pet store.  They didn't seem to be gaining weight like I thought they should, and I began to notice they weren't eating much at all.  I started to experiment to find what they would eat.  Well, it's nothing from the pet store, I con tell you that.  All the eat is "people" food.   I vary what they get each day, so over about 4 or 5 days they get almost everything.  The main part of their diet is dry breakfast cereal, usually whole grain, 4 or 5 kinds a week, like Cheerios, Wheaties, Total, Special K.  The second category is crackers and bread.  They get low sodium Triscuits, graham crackers, and whole wheat or rye crisp breads (these I break into gerbil-sized pieces).   The bread is always whole grain dry crusts.  Sometimes for a treat I spread a little peanut butter on the cracker pieces.  They like unsalted air-popped pop corn too.  Next, they get cooked grains if they are part of the "people" diet--cooked oatmeal, Zoom, and the like, plus bulgur, cous cous, rice, and sometimes macaroni and cheese or whatever if we had it for dinner.  They also get thawed but not cooked frozen peas, corn kernels, and green beans, and fresh fruit like cantaloupe, apples, grapes, peaches. pears, and avocado and fresh vegetables like tomatoes, green beans, cabbage.  They also like cooked (but not raw) sweet potatoes and yogurt.  They are about a year old now, active and sassy, not too fat or too thin, with very shiny, lustrous fur.  Their favorite special treat is a bit of walnut, which I only give them from my hand.  They won't let me pick them up, but that's fine with me because I really don't want them crawling up my arm or getting loose in my apartment anyway.     My real question is if their diet is adequate.  Should I be giving them vitamins?  I don't like the stuff you put in the water because they hardly drink any water anyway, and  I feel like I pour the vitamins down the drain each time I change the water.    Are there other foods I should be giving them?  Are there any that I am feeding them that may be harmful?  And the really big question, why won't they eat gerbil food?  They won't even eat gerbil treats!   Kathleen with Nice and Kind