I have a 115gal with several adult Gourami and several large Barbs, catfish, loaches, etc. I have found that in the 2 years that I've had this tank operational, variety helps. Add a doscile fish bigger than your agressive Gourami. All of my Barbs, with the exception of the 2 Tiger Barbs, are at least 5" long, bigger than my Gouramis. I also have a 10" Bala Shark, the biggest guy in the tank. He is friendly, but his size keeps the other more agressive fish in check, including a 6" Oscar. If you have room in your tank my advice would be to perhaps add a large Bala Shark or Large Tinfoil Barb.