You should feed silver dollar fish 1-2 times a day. These herbivorous fish have hearty appetites, but it's important not to overfeed them to maintain good water quality. Offer an amount of food that they can consume within a few minutes, and remove any uneaten food to prevent water contamination. Providing a varied diet of vegetables, high-quality flakes, or pellets specially formulated for herbivorous fish will help keep them healthy and vibrant.