I have a 6' 125G tank with 1 Green Severum about 4" and a 5.5" Gold Severum, a pair of nicaraguensis cichlids about 4" , 4 angelfish, 6 congo tetras, and a very small firemouth cichlid. Everyone was getting along very good. I added a 2.5" inch male green severum last night and the green and gold severum are chasing him to the corner. I added the male because I thought the 4" green was a female. I didn't see all the markings on the face I have previously seen with other severums I have owned. Maybe it is a male. Anyway, is the tank large enough for 2 green severums to coexist or will he be harassed until he needs to be moved. There is plenty of driftwood and rocks.