Apologies. I've had the clown for about 3 months. Color looks good, eats very well. Dosed copper for 2.5 weeks in a qt tank after noticing the growth. Didn't seem to effect it at all. Hopefully these pics help more.
I appreciate the input. Growth is completely white, looks almost like how mold would grow on some piece of food. Breathing and eating still seem normal so hopefully it'll treat itself like you mentioned.Although fairly rare in this species, I wonder if this is Lymphocystis? That is a viral disease that will often go away on its own - there is no treatment. Key to diagnosing that is there won't be any other symptoms noted, just the growth.
If the growth has a gray tinge to it (I don't see that in the photo) it could be a fungal infection. If the growth is smooth, it could be a tumor.