No, the yellow tang was in the 46 gallon, and I wanted to upgrade mainly for him and one other tang, plus more room for a lot more corals. I just got the powder brown in Tuesday, and had the yellow one for many months, maybe close to 5-6 months. The powder brown went from the box it shipped in, to the 125 float acclimated and the yellow was cought by net and acclimated to the 125 through a bucket. The powder brown was in before the yellow for maybe 30 minutes. I did that because people always suggest adding tangs in together.
Is 2-3 days maybe might not be enough time to give the yellow one time to settle down, but the fact that the powder brown hasn't been eating anything but a small part of algae clip a day.
I was told maybe it was the YT that he didn't eat. I did target feed the powder brown and he didn't eat, kind of swims away from the food.
I have frozen brine that I soak in garlic xtreme, formula 1 pellets, formula 2 flakes, algae clips (he eats little of this, but eats it anyway), and zoo plankton. I think the most he ate is some algae clip, and he did try 1 piece of the flake and I think he spit it back out. Otherwise such as feeding time, he just sits in the rocks and doesn't come out to eat. After feeding time, he is out and about and one of the most friendly fish and one of the least skiddish I have seen out of the bag, you can put your head right by his on the glass and he doesn't take off, so it's not that he's scared of you being near the tank while feeding.
When I got him Tuesday when the lights were out when I introduced him, he was constantly smashing into the glass wall. I don't know if that was to get to know his surroundings or what, but he went to the side of the tank and tried to swim through it, and he couldn't, so then he swam half way the tank length and a higher speed right back into the glass with his nose, seems like he quit that now, but I have never watched a fish do that before.