Juvenile Death!
moving a fish this small is not always a good idea and the quality of the fish is not guaranteed because they are kept in prestine condition where every fish has nothing to worry abouteven the weakest fish will survive, not the same as in the wild where they have to defend themselves and only the strong survive, hanging upsided down is nothing to worry about, I am sure if that fish was not moved from the breeders tank to your tank it wont die, the only way to be sure what caused his demised is to perform an autopsy, this wont even be conclusive.
