The knowledgeable exporters, importers and wholesalers have taken the clean animals and are dumping the diseased ones. The chances of recovery of an animal with visible "holes" in the cuticle are slim and the shop owner should not have accepted it and they certainly should not sell it. More importantly, you should not buy it or even accept it at the much reduced price. I have some evidence that this set of pathogens are contagious and you really don't want to introduce them into your system.
Shell disease is common in the wild, particularly in large males. In the aquarium it seems to be aggrevated by poor water quality, lack of a burrow and strong lighting. Warm temperature also my contribute to this. I wonder if the fact that it is now summer in Indonesia may contribute to the problem, but I have not checked this out.
The only other species that seem particularly prone to this type of shell disease is Gonodactylus chiragra. Hemisquilla seems to have some other pathogen (fungus).
Large individuals always seem to be more likely to come down with bad cases of shell disease - probably because they molt less frequently.
Roy
