Sorry Hayley maybe I wasnt clear. I meant did his fins look like that when you bought him, or have they gone like that?
I am 99% sure his dorsal fin is shredded. This may have been from the guppies he was in the tank with, or your angels here. He needs to be dosed with some melafix to sort him out. You really need to keep a close eye on them, and make sure he isnt taking any more damage. They may look nice together, but you have no idea whats happening when your back is turned, and that dorsal fin is, quite frankly, in a terrible state. I got a betta from a LFS with awfully shredded fins, but his dorsal fin wasnt as bad as that.