Is This Food Aggression? What Do I Do?

I eat all the other dogs food, than guard mine.

Okay, all you dog lovers out there. I am need of some advice. My English Mastiff has been becoming food aggressive towards the smaller dogs. He will be two this summer.

Here's a little background story on Buster :  Bringing Buster Home

I have to feed them separate. At first I thought it was a domination issue. However, I think it is more than that. As if I am in view. He doesn't bother with Moose or Rascal. When I go out of sight even feeding them separate. Buster my Mastiff will go from his food bowl, eat all of Moose's than sit in front of his own, not allowing Moose to eat at all. Same with water.

Twice now Buster has jumped Moose in the house for no reason. Growling, pinning Moose down on his back. Moose of course being a Chug has the Chihuahua mentality of not backing down. Growls back. The sound when this happens is horrible.

Moose did not have anything. No intimidating. No growling. Only playing with the pup. Usually I tell Buster to back off or stop, he does. Last night he didn't. I literally had to hit him to get him off of Moose. I have been keeping them separate. Not allowing them to spend any time together since last night.

I am looking for suggestions. He is up to date on shots, not fixed. I plan on doing that but not at this time. I always have food for the dogs. Plenty the bowls are always full. Is there anything I can do to prevent this besides keeping them separate? I am open for suggestions. i am not ready to give up on him yet. However, for the others dogs and my families sake. I need to figure out this soon.

Other than this I have no issues with Buster. He listens well.