I chop up garlic and combine it with a mixture of mysis shrimp, brine shrimp, whatever I get at the seafood counter at the grocery store, Selcon, and some algae flakes. The fish, including a blue hippo tang, eat the chopped pieces of garlic all the time, which I read somewhere is perfectly safe. My experiences definitely agree with that. But I chop it up, I don't put entire cloves into the tank. The actual garlic in the tank at one time is probably 1-2 tiny pieces.