Weird Growth on Betta

[CalvusAtx]

Picked up this betta today from a lady on craigslist. It has a gigantic growth like it swallowed a marble. It's not pine coning, it's swimming around like nothing's wrong, just wondering if anyone might have seen this before.
Thanks

 

[TheCrazyFishLady]

First off, WOAH.

Second, that looks like a tumor (not 100%).

 

[Mumma.of.two]

Picked up this betta today from a lady on craigslist. It has a gigantic growth like it swallowed a marble. It's not pine coning, it's swimming around like nothing's wrong, just wondering if anyone might have seen this before.
Thanks

To me it looks like he's eaten A LOT. Fast him tomorrow, feed him a pea the next day, then fast again the next day. Also check to see if he's passing anything. See how he is after that.