You could put 10 together with enough space and enough hiding places and diligent maintenance. For that though I'd go with a 75 gallon. If you got two 40 gallon breeder tanks you could split them up into two groups of 5. If you went with 20 gallon longs I would put no more than three in each. Err on the side of more space, not squeezing them in.

When you get them please post pics of the little guys and tell of your experience with Exotic Oddities. I'm curious about both.