Fuzzy Red Claw Crab

Dear Aquaworld,

My freshwater crabs have fuzzy stuff on their shells. They are the red ones.  They have had it for a week now. Is there something I can do?

Shelley Usmial
Sacramento, CA USA

Dear Shelley,

The crab you have is likely the Red Claw Crab (Perisesarma bidens).  This crab does best in brackish water (min. 1 tbls of marine salt per gallon [3.8 l]), and should be given a platform (i.e. cork bark) on top of the water so it can be exposed to the air as they are semi-aquatic.  The fuzz  you see is likely algae.  When the crab molts the shell will be clean again.

Tony Griffitts

Published - 20070331