Some fish will die through stress in transportation or with coping with their new surroundings. A lot of the fish may have been bred in large fully furnished aquariums and when brought into smaller non-furnished aquariums they can also become stressed.
Some stores dont tend to look after their fish that well ive noticed, with a dead fish in every 10 tanks or so. Its quite disturbing when you see 2 young plecs feasting on the wrotten carcass of a guppy. One of the stores I recently found doesnt have a single dead fish in any of the tanks so Im really quite sure Im going to get all my fish from him. The water conditions are somewhat better and the fact he doesnt allow recent fish arrivals to be sold straight away is quite encouraging
