I disagree dragon. Everything on a crowntail is "crowned" and spiked. Even that fin running the lower length of its belly (dunno the name) is spiked.
That fish simply has fin rot.
Here is a pic I got from browsing POTM winners. My betta looks EXACTLY like this except the white streaks are blue.
They don't appear to have frayed fins IME, just spiked.
I'm keeping my 12th Betta... That one has fin rot and is stressed