Little kernels of puffed rice are a great light snack for your gerbil. You can offer these at any time, since each kernel contains virtually no fat and no sugar. In fact, any unsweetened cereal can be a nice addition to the usual pellets. Skip any cereals that have sugar added, since it just isn’t necessary for pets. Instead, opt for the unsweetened, whole grain versions. Test some different options out. Your gerbil might like flakes or other shapes of cereal as well.