I have been keeping cichla for a little while now & have quite a few tanks. I am often moving bass around from one tank to another as they grow out of one & into another. I keep a mix of co-inhabitants & I am starting to believe it has positive benefits on the bass & their coloration. Between creating more aggression (& therefore more color IMO) in the bass, I also believe just having different types of fish/rays/whatever is a big positive for bringing out the best in the bass. The other fish also creates varied interaction similar to what they would have in the wild. Any other opinions I would be interested to hear. (an excellent diet & highest quality water parameters is assumed)