Red Clawed Crabs are living in their own territories,and when possible, in their selfmade homes in the ground.So espesially the male crabs are fighting each other.Because of that it's elemantary nessessary, that enough hiding places are avialable. If not, the crabs often fight to death. Still RCC's are spending much of their time on their own, living with other RCC's seems to be very important.Two males only when enough space for two territories. Better choose at least one male and one female.
As soon as the very young crabs having claws, they begin to fight. Or coming in the new home,evryone has to find a home.And some fights are happening. At the end, sometimes some legs or a claw is lost. But don't worry about. Only both claws missing may kill the crab because there's no way to eat ! When only one claw is lost, the crab uses the first leg like a claw, and climbing is possible again.
It takes some few molts, til the missing part will be grown back again. Because the vesselsystem of crabs contains no veins,it's open, (see also ANATOMY - Respiration system and special anatomic marks) evry claw and leg has some special points of fracture. These are closing immediatly when cutting off and so no bodyliquid is lost.
But it also can happen ,that some more legs are lost, when already some are missing.And finally the crab died.Why that is unknown but maybe it shows a kind of desease.