Thanks for all the great info. I figured I would contribute some.
I have had one yellow tail in a 180 gallon tank for about 3 months now. Normal acclimation, ph right around 7.0 to 7.4, 84 degrees F (dropping that some soon), Tank mates are 5 very large female mollies, red spotted gold severum, red tiger moto, Cuban cichlid, saxatilis pike cichlid, 3 geo altifrons, and a pike live bearer. Food has been small platies and larger endlers/guppies. No problems whatso ever at this point. The Cuban is big enough to eat him, but doesn't seem to like live food. I kept him in a 20 gallon high with a feeder platy for a month while I was waiting for the moto to grow some and he never ate it. The moto loves live food, although she is to small to eat him, but at current growth rate the moto will win the race, so I am keeping a close eye. Same with the sax pike. He is seldomly chased off by other fish as they keep to the bottom 2/3 and he keeps to the top 2/3. I know the mix is not a recommended mix. I like breaking rules and having interesting mixes. I plan on finding 2 more so they school, and I may also add a freshwater tarpon.