Three of my hermit crabs (two red-legged and one dwarf blue legged) have died
over the past two weeks. Didn't see the first two, but the last one was
walking around out of his shell and got eaten. I'd had all of the crabs for at
least three months with no problems. The only other things in the ten gallon
tank are two clown fish and astrea snails. Water parameters are very stable
(amonia-0,nitrate-10,nitrite-0,ca-500,ph-8.4,dKh-10,sg-1.024). Any idea what
could cause the loss of so many crabs in such a short period of time?

Thanks