I have 3 that have been together in the same tank for over a year, and they get along fine, no problems, etc. Their colour has always been green melded with black bands over their back, and I've just accepted that that's how they look, but recently I had to move one of them over to my community tank.
What happened is that they got whitespot (ich) and I had treated them for it, as I always do, but towards the end of the treatment, one of the SAP's started to look really bad, and instead of swimming was just dragging itself around. I really felt badly for it and I just had a feeling if I didn't move it, that it would die. So with few choices as to where to move it to, I decided to move it to my community tank because I've got about 7 dwarf puffers in there and they are fine, no problems with fin nipping, etc.
Well anyway, after only a day of being in the community tank, I noticed that the puffer I moved was really different. He was zipping around swimming and seemed really energetic. When they were in the other tank all they did was swim up and down the aquarium glass, and I just put it down to being nervous fish. They would also play in the strong current of the filter too, but mostly it was up and down at the glass. The one I moved wasn't doing that anymore, it was swimming around, checking out the new tank. But there was also another change -- the colours had changed! Instead of being green and black, with the greens melded into the black, this SAP was now yellow and black, sort of like a bumblebee, with clear bands of yellow and bands of black. No more green at all.
So this is what I'm curious about .... what colour are SAP's supposed to be? And does anyone have any idea why it changed it's colouring like that? They all need their teeth trimmed, and as I'm too much of a coward to try, I'm going to take them to someone to have it done, but after it's all done, I'm considering putting the other 2 SAP's into my community tank. It's definitely improved the one SAP. It's doing things I never seen it do in the other tank and seems really happy. I don't know if it's the size of the tank, because it's gone from a 35-gallon to about a 70-gallon tank, or is it the tankmates seeing as there's all kinds in my community tank? I don't know, but whatever it is, it's doing more good than harm. I'd move them now if I didn't think I'd have a hard time netting them to get their teeth trimmed.
Not sure what I'm going to do, but I will move them eventually.