No confirmed max but I doubt more then 16 inches. 5'x2'x2' should be o-kay but I'd prefer a 6 footer for such a powerful swimmer. Which reminds me, while not necessary; these guys do benefit from lots of water movement.
Water movement wouldn't be an issues with my set up. But I believe you've all told me enough to help me realize I should hold off for now regardless of how interested I am in them. If I had an almost empty tank, I'd go for it. Might grab another small clown loach and a pink tailed chalceus for the upper portion of the tank instead..... and save myself a few hundred bucks lol
I believe they are not yet breed in captivity. Also, the area of collection is difficult to attain these species, same area as intermedia cichlid. Simply supply and demand. Anyone have a more specific answer?