Just thought I would mention, I have used the tetra fungus guard a few times now... And I really like it! I had bought a whole school of infected tetras, didn't know they had cottonmouth, by the time I got stuff for them I had lost all but one. Used the fungus guard, treated the entire tank and have not had a problem. Now it seems my tetra has tail rot, and is very very pale. Just treated tank again with fungus guard... We will see how he is in the morning! 