I don't know - a lot of people seem to keep them in the small plastic containers seen on tm with fighters in them. I have also seen them floated in the top of tanks but apparently the fighters will jump easily out of them.
The biggest thing about breeding these is you don't know how many you will get. My latest spawn has 2, the previous over 50, the next 13 and the one before a couple of hundred. If you only get a few space won't be an issue, if you get a lot you're going to need a lot of tanks.
I've just come from turning my tank lights off and I found that a couple of my 8 week old fighters had been fighting judging by the state of their fins. Even though they have been raised together this group is obviously not going to be able to stay together and so I have had to seperate 4 males off tonight.
they range in size from 2.5cm - 2cm.