Hey Bruce! Very nice looking pyxie! I have a male and a female, and I keep them in two different tanks. They can see each other, and every time one moves, the other one will strike, bonking their nose on the glass. Male pyxies grow quite a bit larger than females, and usually, in the amphibian world, anything smaller means dinner. I would recommend keeping more than one pyxie separate unless you intend to breed them.