I have a 75 gallon all male tank that's fairly established. About a month or so ago, i introduced an OB and a Eureka Red. The OB handled it ok but the Eureka did not and i had to remove him. I don't think he had really settled in from being shipped to me a couple of days before. He has been in a quarantine tank since then and is doing very well. I think he is stronger now, used to my food and feeding routines and hopefully ready to be re-introduced.
My plan is to
1) bring up an empty 60 gallon that i have and move some (maybe 1/3 or so) of the existing stock into it
2) rearrange the 75 gallon while doing a water change and then introduce the Eureka along with a Green Phantom Pleco that I picked up
3) After some time *, re-introduce the rest of the tank that i had put into the 60 gallon.
* My question is how much time do i need to make this work? I plan to do steps 1&2 this Saturday morning. I'm hoping that Sunday around noon (basically just over 24 hours) would be enough. I want to be able to watch the tank for a while after reintroduction to make sure everything is going well. I will be off from work on Monday and Tuesday, so I could put it off until Monday if that would be better. I would probably not want to wait past Tuesday as i will need to put away the 60 gallon before company comes.
i realize it's not ideal but the tank is full, so i won't be adding any more after the Eureka. One way or another he will either have to join the others or I'll have to get rid of him which I definitely don't want to do. He unfortunately just wasn't ready last time I introduced him. As part of this transition, I will also be permanently removing two of the somewhat more dominant fish in the tank (a dragon blood and an otopharynx tetrastigma) so that should help. probably the main fish of concern will be another dragon blood (that's staying but i don't think gave the Eureka much trouble last time), a star sapphire and a lemon jake. the tank boss is a red empress but he is usually more of a benign dictator.
I can wait until Monday to start re-introducing fish so that will give the Eureka two days to get acclimated to the tank. Hopefully that will be enough. Maybe i'll also keep the temporary 60 gallon tank somewhere where i can keep it going longer if i need to....it won't be near the main tank which i originally wanted but it will give me more flexibility on timing.
Well, so far, so good. I moved out the 4 fish to quarantine on Saturday morning, big water change, rearranged tank, and introduced the solo peacock (Eureka Red). I had left the tank boss (Red empress) and number two (Dragon blood) in the tank so that the order of the whole tank would not be messed up. Since they were already at the top, they didn't mess with the Eureka too much and things settled down by Saturday afternoon. By Monday morning, the star sapphire and lemon jake that were coming back looked a bit worn in the 30 gallon with the two that are leaving so i decided to put them back in the main tank. It was just enough time (in my case) for the Eureka to have been comfortable and for the lemon jake to have lost some confidence so they sparred a bit but by Monday afternoon the whole tank has settled down. Every time the jake and the Eureka went at it, the #2 Dragon blood or the #1 Red empress would break things up.
I know things may still take a week or two to know for sure but things look good right now. I also have caves and tunnels and plants for fish to break site lines and get away. Also I have some non Malawi in the tank so they are less interested in the solo peacock which helped.