Growth On Goldfish Top Fin

[platinumfish]

Hi, first let me say that I have searched here for this topic.
My goldfish about 7 -8 inches,may be 3-5 years old, has a good size growth on its top fin.
Other wise seems fine ,eats good, swims fine. The bump just came up. It is seen from both sides of the fish.
I cant say it looks califlowerish, kinda looks like a pimple.
It has another goldfish and 2 parrot fish in 55 gal tank with it.
Please help.
Thank you, Lynette

 

[WILDER]

Any redness to the pimple.
Can you issolate and use a bacterial med.
Lumps and bumps that suddenly appear are usually bacterial.

Lymthocystits can look like a cauliflower, smooth looking lump, cluster of eggs.
Comes in the colours of pink, white, brown.

What are your water stats in ammonia, nitrite, nitrate, and ph.