I have two goldfish and two mystery snails. Fish get fish food and snails (and a couple shrimp) share an algea wafer. The only problem is that the goldies love to play with the algea wafer. They're either eating it or playing with it until its all disintegrated. Ontop of that all the goldfish do when they're not being fed is scavenge the gravel for food so I'm not sure how much excess food is even left on the bottom for the snails and shrimp to scavenge. Should I just leave it alone and trust that the snails are taking care of themselves or are goldfish just not good at leaving scraps for scavengers?