You'd have to crush whatever you want to feed them to a powder or as close. I have a mortar and pestle which I used to crush flakes and pellets. I haven't tried with algae waters I used high protein flakes made from worms but I haven't had success with supplement feeding. Initially, they didn't seem feed on it so you definitely need live algae growing and present in the water for them to survive.Can you supplement with algae wafers?