Strange bump

[ASHNichole]

Tank temp 75°
Ph- 7.4
Nitrate-0
Nitrate-0
Ammonia-0
Hardness-150
Alkaline-120

 

[Andy Sager]

It appears to be a tumor. Sadly, they are very common in goldfish these days. There's nothing you can do about them. Eventually it may cause a problem or grow larger but where it is at, it should not cause any issues past swimming if it gets too large into the tissue. At that point you would have to decide whether to euthanize or not.

Hope this helps