I special ordered 2 from my lfs and when they came in they were about 10 inches from the top of there fin to the bottom. To keep 1 let alone 2 you would need a very large tank. They need room to stretch there long fins, and plenty of room to swim. They are butterflies so naturally they are picky eaters. i would not suggest putting them in a tank smaller then 75-100. Due to the fact that they get SO TALL. This is IMO because I have seen how big they get. I decided that my 46 was way to small. However I have never kept them.
HTH
Leopard