Hello,
I do not think this kritter keeper is a good idea. Water quality is hard to handle and I can not believe that the pair will breed in this tiny box. And the box is too small to raise up the offspring. If you want to breed in this aquarium, it is possible to divide the aquarium with fine foam filter material in two, but in my opinion the best way is to buy a second aquarium (25l).
Greetings
Patrick