Can I do anything about my Pitbull/Blue Heeler mix stop being aggressive towards my German Shepherd mix? He is always wanting to fight him and I have never ever taught them to fight. I AM VERY AGAINST THAT.

There are several issues here. For starters, how old are they? Are you sure it is fighting and not play? Here is a picture of a couple of friendly young dogs enjoying having another young dog to play with:

http://www.photolocker.net/images/La...llaplaying.jpg

Are their hackles raised, lots of low rumbling growling at first, yelping, fast quick bites, bits of fur and skin taken off, hard to break up, etc. The loser flees? Those are bad signs.

If it is real fighting, neuter them if not already. No reason to have intact mixed breeds. Seldom a good reason to keep pure breds intact.

Finally, if they are fighting for second place, it will be less worth while. The key to most behavior problems is approaching things using the dog's natural instincts. Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog. Life is much easier if the 2 legged pack members outrank the 4 legged ones. You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at Raising Your Dog with the Monks of New Skete For more on being top dog, see Establishing and Keeping Alpha Position, Letting your dog know you are the boss

Unfortunately, if you put 2 of the same sex together that have a strong dominance drive and dominated their litter, even the best dog handler may not be able to keep peace.

I am glad you are concerned about this and opposed to the fighting.

The German Shepherd/mix is 3 yrs old and the Pitbull/Blue Heeler is 2 yrs old. I know for a fact it is fighting because tha Pitbull/ Blue Heeler has knocked the back of the German Shepherd's head against the wall and knocked him out. He carried him around in his mouth and that is when I luckily got home. I WILL Neuter them both ASAP.
Thank You so much for the other advice.