no, he is all by himself. as said he is a Veiltail betta, its his rear fin that has missing part and its not like hes eaten from end up the whole thing, its the back half of the fin that has half missing. i hope that makes sense.
if you think about a VT blowing its tail out and it being cut in half longways, its the back half that is half as long as the rest of the fin. looks strange, there are a few long spike hanging off it and a couple of bits of fin on the bottom of tank.
he is still swimming well.