When To Stop Medicating For Fin Rot?

[geer head]

So, I bought some fish and about a week or two later they got fin rot, but my danio's that share the tank with them didn't.

I medicated for about 9 days and their fins still are very damaged and possibly look a bit white on the edges... When do I know that it should be safe to stop medicating for fin rot?

 

[WILDER]

How many gallons or litres is the tank.
How many fish and which type.
Water stats in ammonia, nitrite, nitrate, and ph.
Whats med are you using.