if you use an aquarium you must clean it every day or the ammonia from poo can build up and poison the birds. the best thing for bedding is aspen or pine shavings, you can use sand but do not use paper it is too slick and they can hurt their little legs on it. You can use the nonslip shelf liner that is sold in the housewares areas of most stores. it made by Rubbermaid and works really well as it is washable and reusable.
One last note, buttons really do better in single pairs, one male one female. Especially if you want to raise more. Good Luck.