What do you feed miniature frogs?

In cleaning out a space that was vacated by a tenant, we found one of those cubes with water, rocks, bamboo and the tiny water frogs. I'm sure you've seen them in malls. They also sell those really colorful fish in the same containers. The previous tenants had just left them to die. No one here has ever had them before. Do we just give them a bit of regular fish food?