Cyst? Pox? Need help with a bubble on my fish

[Ana]

Recently noticed my fish had a bubble-like cyst in it's body, and was afraid so I separated him from the pond just in case it was viral.
Its been around two weeks since, the bubble is looking a bit uglier than before, but he fish Is still energetic as ever before, and isn't acting sickly in any way.

I mean it's not normal but, is it normal? Is it safe for the fish and the others? Could it be a tumor or something contagious

 

[GBBUDD]

Unfortunately gold fish come down with these lumps with no rime or reason. I was actually watching a goldfish video just last night and a breeder said he ran two different preactive medications for all his gold fish and i have to admit he had some beauties, but he never said what he did but this will tell you there is some regiments that the pros do.