Am I using the right food in my aquarium?

I have a freshwater 10 gallon tank. I have a red platy, a tetra, a glofish (i did have two but one didn't make it through the first night), an african dwarf frog and a yellow snail. The store recommended a basic tropical fish flake, which the fish love; but I'm worried about the frog and the snail. They have lived for 3 weeks so I'm sure they are eating something... but I watch them and can't tell if the frog is getting much. Also, the snail moves around a lot so I wonder if that's normal or he's searching for food.. Anyone that can help with this?