In my earlier comment I gave my experience with Corys and Melafix. After I put the carbon back in the filter, did a water change, and increased the air pump, within an hour nearly all the foam from the Melafix was gone. Five of the Juliis out in the open that I could see had become active again. I don't know that it was the Melafix, but that was the only thing I did different since adding them to the tank. There are also 13 neon tetras in that tank and they didn't seem to be bothered at all. A note: the reason I added the Melafix was the recommendation on the bottle to add it when adding new fish, not because I noticed any stress. I will be very careful with this in the future.