I think he may have been providing you with a broad spectrum cure to reduce stress on the fish. melafix is good for that.
what you should get is salt and white spot cure.
raise the temp.
melafix is useful to have around the house any ways.
is returning them not an option? did you call to ask if their danios have white spot?
see this is why i have a uv steriliser in the tetra-danio tank :lol:
my numbers have dwindled. but i refuse to buy more clown loaches until I see some quality stuff come in again. Im so tired of ordering loaches to get tiny, skinny ones arrive one after the other.