If you want to try it in one, then you just need to consider the needs of the two different species and decorate accordingly.
Multifasciatus are smaller, and they live in areas of the lake with a very high shell density. Their portion of the tank would be large numbers of smaller shells that the brevis may find unsuitable. Likewise Multifasciatus are colony breeders, and live in higher numbers.
Brevis are quite the opposite, they come from areas of the lake with a very low shell density. So low, in fact, that a male and femal pair will often share a shell, something you won't see with many other shell dwllers. Their portion of the tank would contain just a few larger shells. The fish themselves also live in lower numbers.
For the greatest chances of success it would be best to form a rock pile down the middle of the tank so that each species can live without being in constant view of each other.
I have not tried to keep these two together, so I don't know how it would work. In truth, I have my doubts--fish rarely go willingly along with our plans, and despite our best efforts you may find territorial diputes get out of hand. If you decide to do it this way you should be prepared to set up a second tank if it doesn't work out.
