yeah I had them in a vegebin/breeding container I use to grow out little fish before I shipped them, would probably keep them in 2ft until around 2-3cm's, you will know when to move them judging by how argo they are to each other.. They're pretty good at hunting for food after a few weeks but will grow faster if in a smaller one and you pump food into them..
Dixon, sorry to hear shipping is too expensive for you, bear in mind I could ship 24 in the $30 I quoted you for shipping so you could get it cheaper if you found someone else who wanted some in Chch (im actually shipping some down there when they're ready), im sure someone down there is breeding them though, id seriously recommend you do invest in more than 12 of them no matter how poor you are any less and its most likely end up in dead fish.. Good luck!