Shrimp question

[mbeach66]

hey everyone,
I've had my tank up for about 4 months now and had my Blood red fire shrimp included for that amount of time too. Recently, he has developed black marks on his outter shell. When molting time comes around the outter shell is lost and the black disappears but however returns on the new shell layer a few days after molting.
any suggestions as to what this is, or if it is a matter of concern.

Thanks, MBEACH

[tendar]

I odnt think it would be of a consern unless it was acting stange or dead.