Your tank's about the same size as the tank I'll be going for. Do they kill each other off like their cousins? Or would you say that even keeping a single one is worth it? Do they have much better colors?
Their colors are more vibrant and more blue than green. I haven't owned them but as I mentioned for years the same group was in a LFS tank. They also sold them in their fish section on a regular basis and they were always 3-4" in size. I never saw small ones for sale.
I don't know about aggression within a group but due to size I wouldn't put them in anything less than 90-100g.
Most of the other local stores at the time sold the tiny viridis which would die off fast and not from aggression.
I also think a lot has to do with capture and what these fish go through to get in a retail vendors tank.
Yes, but I would probably get at least two.
It would be good to have other dither fish, anthias, wrasses, ect. if you're only getting one.