Help! Bad finrot on guppies


New Fish
Feb 12, 2018
One guppy has a streak of blood in his tail, three large slashes and discoloured (almost white) patches on his tail. The other guppy has a very ragged tail and is losing sections of it fast.

I vacuumed the gravel as I always do when I clean the tank and did a large water change. I don't know the pH level of the water as I don't own a checker but will buy one soon. (I have had these fish in the tank for about a year now with no problems though)

I tried using 'wardley fungus-ade' medication as their finrot seems quite advanced. It has only been a day since putting the medication in but my fish seem to have gotten worse rapidly. The medication says it treats finrot, but maybe I need a bacterial medicine, rather than a fungus one?

Aside from the finrot, both seem very energetic and are still eating.

Any suggestions on how I can cure this?