St. Bernard agression w/ other dog in home

Question
Our family adopted our Saint Bernard Barney almost a year ago from a rescue. He was about 18 months at the time. We have 3 golden retrievers(2 females and 1 male) and 1 male Saint.  Barney quickly became #2 in the dog pecking order.  Our oldest female, a Golden is alpha.  JJ (our male golden) was moved down after Barneys arrival.  In the past few weeks Barney and JJ have been fighting. It is very frightening to observe.  They seem to be trying to kill each other, but when the "fight" is over, there are no bite marks on either.  Help!

Answer
The best way to deal with type of problem is to buy muzzles for both dogs and let them 'sort it out' with the muzzles on so they can't harm each other,but until they sort out what dog is in charge the fighting will continue. I have used this method for several years now and it seems to work