I have my Red texas with a red texas turned green, jag, Pbass, Parrot, and a jack . he became very aggressive to all of the other fish even to my jag, which was larger then the red texas. so i took him out and put him in his own tank and he was not happy being by his self . Then i put him back with the same fish after about 3 weeks, and he is not so aggressive anymore the jag is even the owner of the tank again it is much nicer now.