Well, the assembled clown-committee on this thread nailed it. After a quarantine, I put the new clown pair and the leather coral they were hosting on the far right extreme of the tank and everything you all said would happen did happen. The small male started hanging out with the other female, who nipped at him now and then until his original mate came and got him. The females spent time in the other one's corner of the tank and there was some minor fighting with no damage, and now a little over a week later and there is peace, everyone seems happy with half the tank as their territory, the original pair is still together, and no one is dead. I'm so happy that worked out. Thank you again for your wisdom and advice @
Chanjad385, @
eatbreakfast, and @
Christopher Davis
The only unfortunate side effect is that now I have a new unwanted decoration in my display tank because it makes the clowns happy. In order to make sure there were no parasites or hitchhikers on the rock and leather coral, I separated it from the fish and had a coral Quarantine Tank and a fish QT. I put PVC pipe in with the fish for hiding places, but couldn't resist buying a Spongebob pineapple house I saw at PetSmart for the QT tank as a joke. The clowns started living in that. I figured they'd switch back to their leather coral in the display tank. Once in the DT, though, they really didn't go for the leather coral, so I thought maybe the added protection of their QT house might be a nice option, and maybe it would encourage them to accept that half of the tank as their territory. I put the spongebob house in the display tank and it worked. They are adjusting to the new tank and have accepted that corner of the tank as theirs. To my horror, they still have not gone back to hosting their leather coral, so now I have a stupid Spongebob house in my DT and don't know what to do about it. It's in the back behind a rockpile and partially hidden by corals, but still....