Well,it's a horrible situation. A violent male JD and a male gt who is just pushy. In a 39 gallon ONLY untill I get a 120 in a few weeks. Bot fish are adults. Decoratoin is basically a divider. Any wy to take down the divider? I have acess to a rockyard so I can provide cover.
I'm going to say no in the current tank. they probably dont have enough room to decide who "owns" what part of the tank. However, I dont see that being a problem in the 120.
as long as they arent causing damage to themselves or each other, it should be ok as temporary. Maybe put a plastic plant in front of the divider on one side so its harder for them to see each other.
Keep up on those water changes. Especially since they're adults.