They have a very small bioload, so I would say at least 7? I know of people who have about 14 of them in a 10G and are still able to maintain healthy parameters
they are just like CPD's though. They have to get used to you. The first week or two they're super shy an scare easily. But in time, they will get to know you and usually greet you
the males get extremely bright when showing off to females. The male that gets really bright, is the alpha male. Their colors are even more beautiful when fed a varied diet ex: BBS, Artemia, and crushed up flakes. They're super curious too! If I have my hand in the Tank, my school will swarm around me and circle my arm lol oh, and they liketo play in the current of the filter