Throughout my experience with dealers, they're highly susceptible to disease when mixed with other tetras that may be carrying something. Because of that I would contemplate purchasing them from larger chains that have most systems plumped together. That said, die off rate is higher than most tetras which may have lead to some of your smaller shops not carrying a good qty of them. The only store around here that always has a good amount of rummys isolates them in a separate tank ...as they do with other select tetras. Goodluck in your search!