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I have 2 panda cory's that I bougt about 7 months ago and they always swamm around together so I thought they might be a pair. I am not sure about the sex but one is larger than the other. Just a few days ago I noticed that the larger one was always hiding in the cave and the smaller by itself and it's whiskers look like they had been chewed off and the fins were torn up pretty bad. Do cory's fight when they spawn? Is it possible that female is guarding a nest of eggs inside the cave? It just seems strange because I have 5 other peppered cory's and none of them look beat up.

My experience with spawning corys is minimal, but no one else has answered this yet so I'll have a go. As I understand it, when two corys pair off to spawn, the male chases the female around and rubs his head against her; this is his way of prompting her to release her eggs. His intent is not to fight with the female or harm her, but in my experience, females do tend to get a little banged up from this. They may also attempt to clean off a rock or other flat surface, using their nose and barbels, and this can result in the fish getting rubbed raw. The female also will likely retreat to a quiet spot for rest and recuperation after her ordeal. Also, corys don't guard their eggs, in fact both parents will quite readily eat them if they are not removed.

At any rate, it doesn't sound to me like what you're seeing is anything out of the ordinary. You will of course want to watch the female's injuries for signs of infection, and pristine water conditions are your best defense against that. Good luck, and I hope this helps!

I would look at other fish in the tank to find the guilty ones. It's almost certainly not the other Cory that have done this.
In my experience, Corys never harm eachother. I have lots of Corys and have been keeping them for a long time, and I have never seen any of them as much as nibble at each other. Not even during spawning or anything else. I have at least 50-60 Corys, and no one has never been hurt by another Cory.

As mentioned above, Corys have no parental care of eggs or fry and often eat the eggs if given the chance. Sometimes they do, sometimes they don't. I have experienced both with the same group. Sometimes they eat all the eggs after a spawning session, and sometimes they leave the eggs untouched.

You wrote that the whiskers look to be damaged. This is a very serious matter for a Cory. When the whiskers are gone, they can't smell the food. They are totally dependent on them for both search for food and for the spawning ritual.

The whiskers can be damaged for a number of reasons. Often the substrate in the tank can harm them, if the substrate is sharp edged gravel. It must be fine sand or well rounded and smooth gravel, no sharp edges! That can actually cut the barbels off.

There is also a disease that attacks the barbels, but ufortunately I can't help you with that since I've no experience on that. But it is possible for the fish to grow the barbels back, if you do something about the cause. The barbels may not grow back in their full lenght as before, and it takes quite some time - but it is possible.

PS!
You are aware of the fact that corys are most happy when kept in groups of at least 6 or more, not just a pair...?

Mona, I respect your experience with keeping and breeding corys, it's far greater than my own. Having witnessed just one spawn among my own fish however, I must say that it is indeed possible for a cory cat to suffer injuries during spawning. My female c. aeneus' nose was rubbed raw after spawning. It healed fairly quickly, but it was definitely the result of raucous behaviour during the spawn. I doubt the injury was directly inflicted by the male (I don't think corys have the means to harm each other, even if they wanted to) but I don't think spawning-related injuries are out of the question. I've seen it in my own tank!