Red Claw Crab Disease?

[Lil Tank]

Hi All! I am new to the forum and I need a little help....

I have a red claw crab in my aquarium (don't worry, he has a place to go for air) but he is getting a white almost chalky looking substance on his back and it looks a little puckered.... At first I thought it was just him starting to moult (I've only had him for about a month) but now I'm not so sure.

Anyone know what this could be?

 

[iliveinazoo]

It could be calcium deposits if you have hard water?

 

[Lil Tank]

I check the hardness regularly. If anything, it's a little more towards soft....

I did find a full moult from the red claw this morning and the white stuff seems to be getting less so I wonder if maybe it was part of the moulting?

 

[iliveinazoo]

I check the hardness regularly. If anything, it's a little more towards soft....

I did find a full moult from the red claw this morning and the white stuff seems to be getting less so I wonder if maybe it was part of the moulting?

I used to have a fiddler and I've got to say that I never noticed his shell whiten prior to moulting but he did used to go into hiding around the time leading up to and just after moulting.