Hi
I am In no way saying to do this its just an idea and purely an input only.
I like Joby have not had enough experience with this but I have searched on the site and it seems that the damage done to the body will almost clear up with very good water conditions and frequent changes,in time.
I agree with Joby that they need to be separated from each other as soon as poss ,I expect it is fish No 2 and that it is fighting with what you call fish No 1 poss alpha male and look to each other the same size which is probably the cause of the longer period of fighting, as in this pic.
http://www.zebrapleco.com/forum/files/t ... ni_662.jpg
If you have not got a way to separate them the other alternative is to rearrange the caves so they are more distance from each other or put a rock or wood between them so fish cannot see each other or able to swim from cave to cave in a strait line if not that section off from one an other.
The damage to the fins will probably be helped with a dose of something like Melafix.
This is just something I would use and done with caution maybe half dose not sure ?.
I do know this does help the the growth of the very damaged fins on other types of fish that I have,I have used it on my zebs and its been ok but just to help condition them.
Deep breath
Now as for the lump on the head I am almost certain that you purchased the fish with the lump on it looking back at the markings of the fish on the left from this pic(not clear but I think it is).
http://www.zebrapleco.com/forum/files/t ... 46_179.jpg
That means it was probably born like it or sustained an injury before you had it.
This has grown a bit and doing anything about it will not make the lump disappear think it will have to live with it if it pulls through its got a good chance its in good condition other than the damage.
Sorry to be long winded and hope this helps.
Jerry
Caution is a most valuable asset in fish keeping, especially if you are the fish.