RE: What's wrong with this carp?
That's called a 'mirror' carp.
It's a common carp, but with funky scales. It's genetic and occurs naturally in the wild population. In Europe certain strains of domesticated carp are bred for this trait. (it's fairly rare in our wild populations, tho' some areas have more than others) I've shot a couple here in Northern IL.
There is also what is called the 'leather' carp, it's another genetic anomaly in which the carp has no scales or just a few scales along the fin edges. They are rarer than the mirrors and I've only seen one in the wild.
Congrats on your unique fish!