HCA: Hermit Crab Association

I've read bits and pieces on here about iodine in crab diets and it's left me pretty confused. In a nutshell, I read the following;

Iodine helps hermit crabs molt - too much iodine can cause poisoning.
Iodized salts are bad and shouldn't be used - salt water contains iodine which helps in molting.


What does iodine actually do during molting? How do I ensure my crabs get enough iodine, but not too much? Are the salts sold for marine aquariums iodized, or do they contain iodine naturally?

Hey, long time!!

Its not so much the iodine in salt, its the anti-caking agents that are in them that are the trouble. So avoiding the anti-caking agents is key.

The salt we use for the water has iodine, but its not out of proportion to the other minerals in the salt, as its been either dehydrated off from sea water or its been chemically mixed to ensure its pretty identical to sea water. The sea salt that people use in their food, as long as it doesnt contain anti-caking agents, is fine to sprinkle a bit in their food. I use "Red Sea" I think its called.

I think if you offer salt water on a regular basis and then some sort of seaveggie with every meal, they will be fine. Another thing you can look into is a lava stone (I have one of the ones that are for birds in my tank) as it too is a natural source of iodine. Mine love it and are regularly eating it, more so after a molt I have found.

I don't think the crabs can get too much iodine if it is in its natural form (not an additive as in the case of table salt). Any sort of fish or seaweed will have a natural balance for safe consumption levels of iodine.

Thanks for the info you both! I use the Red Sea salt aswell, I'll look into the lavastone.

Still leaves the one question, what iodine actually does during molting. Is it used like some sort of disinfectant like we use it, or differently?

im not 100% on this but I think iodine is needed for getting the skin all the way off.