I have 3 neon tetras that are showing disease and I am having problems solving it, can anyone help? Started with 2 neons a month ago - one has cottonmouth, one has white on its fintail. On advise, used Interpet Anti Fungus & Finrot, but after using it twice there's no improvement, plus another neon is showing signs of illness. Should I give another dose or would something else work better? Also I have guppie fry in the tank; will this or any other treatment hurt them? Thanks for any help.