Iodine Supplement for Bamboo Sharks

[Taaron]

I have 2 Small Bamboo sharks and they are doing just great eating well and everything. I have read alot about these guys and know almost everything you can read. The only thing I can't seem to find is how to supplement there iodine, do i just add it to the water or do i add it to there food? The reason I ask is because if they don't get enough they can develop a goiter on there neck and if it gets bad itll prevent them from eating and will eventually die. I just want to make sure these guys live healthy lives right from the get go. If anyone knows alot or has alot of experience with sharks let me know, Ive seen supplements on the internet for them, just very expensive is all. But if thats what it takes then i'll get them. Thanks.