Usually if you provide enough hiding space they will be ok, well some of them will. If you really want all of them, then yes get another tank like a 10 gall. I had mine in a breeding net and they were pretty small. When I moved them in the 10 gallon w/my others they grew pretty quickly.
When they are about double in length from when they were first born they should be ok depending upon the other fish you have in your tank.