Betta fish attacked by snail?!

Question
I have a crowntail betta and a small apple snail in the same 5 gallon tank. I was at first worried when I got the snail because I thought that the betta would bother it, but it seems to be the other way around. They've been together for 2 months now but I recently left to go home for Thanksgiving for four days. When I came back today, my betta seemed to be hiding in the corner under his castle decoration (weird behavior for him). When I took him out to clean the tank, I noticed he was bleeding. When I looked at his body, I saw that he was missing two pieces of his very bottom fins (near where his anus would be). I found the pieces in the tank and the look like they were chomped off. He will come out if I tap on the glass near him, and he really isn't eating. I keep offering him food and he looks at it, and then swims away. I wouldn't put it past my snail, he's pretty fearless and isn't afraid of my fish at all. I don't know what to do, whether it could be something else and whether the fish needs antibiotics?

Answer
Noelle,                                                      Your snail is not attacking your fish. They may eat fish eggs though. He isn't doing much for your tank anyway .. they are just eating and pooping. It is mostly for looks...He may be rubbing against his plants or decorations. He may even be biting his own fins off. They do this and noone really knows why. I think stress. So you may want to get rid of the snail or his decorations.... Good Luck,Tina