I also gave red crabs, not sure if they are dwarf.

I don't have iodine, but I do put a 1/4 teaspoon salt every 25% water
change on my 33 gal tank, thanks to elaine sugestion.

The crabs are doing fine, one of them has molted and the other I guess
should be doing it shortly too. How long between molts by the way?

I just lost a ghost shrimp, with the white syndrome. Not sure if it was
white before he died or not, was not there to see it.
But my water change with the addition of plant fertilizer might have
something to do with it.

But the other one I have has molted once and it looks good.
Got two more today.
Love those fellas.

So I am not sure if iodine or salt is the reason why they die.