I have posted this in other threads.
The Bartletts will not survive over time in your 180 so please save yourself some time and money and do this instead. For over thirty years I have kept many types of Anthias in many different tanks. Some mixed group types, some single groups, in mixed reefs with other fish and anthias only reefs. Some things I have learned the hard way but can save you time and money are listed below:
Lyretail are the hardest but also one of the most aggressive.
Bartlett are the most attractive in a group but fight amongst themselves and isolate the weaker, one at a time and starve them until you eventually over time only have one Bartlett standing.
In the end, in a display tank of less than 300 gallons, your best bet is to get 6 smaller lyretail females and let them figure it out for themselves. In my current tank, two changed to male after a few months. The larger male is the dominant one and the slightly smaller male stays out of his way. They all seem to fight at first but the dominant male controls the females, chase them but does not isolate or kill them. It seems to be a working situation which is the only permanent one I have found.
I'm sure some will not agree with this but all I can tell you is this is what I have found after trying different combinations over time.
