My fantail goldfish had a fight with the filter and I would say he lost,?

But he's persevered, and by fight I mean he wedged himself under it somehow, and got suctioned onto the intake. When I woke up and noticed I thought maybe he died and sank and got sucked onto it, so when I shook the filter he went swimming right off of it. He seems to only have suffered damage to his fantail with about half of it missing, will this grow back and will he be okay? His side was a little distorted at the points where they were being impressed onto the filter bottom but they have gone away with no noticable scale damage. Is trauma/stress something that I should be concerned about also? HELP, I love my little spazzy fishy and would be sad to lose a fish with his personality!