Sick Fish And Threat To Tank?

Anyone have any idea what this is

 

I am no expert by any means but it looks like a tumor of some sort the way it protrudes out like that. Did it just appear or has it been growing?

 

Just saw it yesterday haven't noticed be for

 

Any way for a better picture? Has his stomach always been that swollen or did that show up recently with the dark spot?

And it's hard to tell in the picture (for me at least) what color is the spot? Like I dark yellow? Or more Brown?

 

Is a grayish color. The belly has always come down but hasn't always had the bump on the side that's new

Closer look