Hi.. I have one 5-6 inch red belly in a 75 gallon tank, I was wondering if I could add another one of the same size with out problems? I got the one about two weeks ago. If I keep them feed well will they still eat at each other or try to kill one another to be boss of the tank with just two? I would get three but three 10-12 inch fully grown seem just to much for the tank size? What do you guys think??