Hi all! I'm new here and looking for some advice.
I've got a goldfish who has recently developed a myriad of problems.
To set up the story - I've got a Biorb 60L, 2 fantail goldfish - Phil (at least 13 years old) and Vinnie (just a youngster at 5).
In the last 2 months Vinnie has been getting what I thought was a recurrent fungus growing from spots on his gills, pectoral and pelvic fins. The white spots appear and then a day later there is whispy white stuff growing out of them.
Originally, Vinnie got cloudy eyes then developed whispy white growths, I treated the tank with a Biorb cure all 'first aid' filter cartridge, improved water quality (not sure why but ammonia had raised and pH had dropped). One of his eyes improved but the other remained partially covered, the whispy stuff disappeared.
Then the white spot/growth thing started - again, first aid cartridge seemed to cure it.
3 weeks ago...it came back. Faith lost in biorb cure all, I moved to Pimafix for 7 days. This not only cured the growths but his eye is now unclouded!

3 days ago...white spots and then sprouting again.
I'm using the pimafix again.
Water quality shows pH 7.1, no ammonia or nitrites, nitrates of 40ppm.
Is it even fungus? Is it something parasitic?

Oh, Phil (the old man of the sea) exhibits no symptoms, spots or growths (but he is white, having lost his colour many years ago - so maybe I'm just not seeing it)
Vinnie doesn't act sick - eating fine, swimming fine, not lethargic and not rubbing against things.
Help
