Great thread! I recently got an indo regal which is hanging out in my frag tank. He's eating pellets aggressively and looking at flake and mysis (which is better then the juvenile imperator in there that is only eating frozen mussels).
They hang out together and have been doing great. After I got the regal, however, I got an opportunity to buy a pair of regals that has been in captivity for 4 years and was actually collected together.
I've gone from no regals to a possible trio. I know Copps had a trio but I believe he added them separately. I know others have had pairs that they either introduced together or separately.
My concern is that since the pair is a bonded pair, I wonder if they'll accept a third. My thought was to get the single eating well and then introduce him to the display. Then introduce the pair to the system as well. I figure since he'll already be in there, the single will be less likely to get picked on.
Any other thoughts/suggestions?
So, thought I'd update for anyone else since I didn't find a lot of info when I posted this originally.
I got my single fattened up and eating after about a month or so (he helped my imperator start eating out of the water column). Then I added a pbt to the frag tank and the three hung out together without a lot of aggression.
I'd decided to get rid on the single after talking to a couple people and reading more about their behavior in the wild (rarely found in trios).
I put the pair in the tank with an eggcrate divider to make sure they were doing okay before getting rid of the single.
Initially, the larger of the pair was somewhat aggressive towards the other fish that were in the tank and would display at the eggcrate barrier. The single from before and the smaller of the pair seemed interested in each other and were not aggressive.
I got them acclimated and then went to bed. The next morning, to my chagrin, I couldn't find the smaller of the pair. After a little search, I found it swimming with the single. It had gotten across the barrier overnight. The larger of the two angels was not happy with this change. After seeing this, however, I fed and then slowly removed the barrier. After a little initial displaying, everyone seemed to settle down. The PBT displayed some but everyone seemed to get along.
Over the last 2 weeks, everyone has seemed to settled into a routine without any noticeable aggression. Yesterday, everyone looked fat and healthy and got moved into the display. So far, the regals generally hang out together, though the pair seems to be together more often then the trio. The imperator also seems to hang out with the single some.
No real aggression with any of the other fish other then a little displaying (though the PBT hasn't fared so well and has been continuously harrassed...will hopefully die down soon).
So, at least in my case, having a pair and a single and putting them together has worked out really well. I'll try to post a few pics next time I take a pic of the tank.