iodine/iodide aids molting in shrimps, without which, might lead to molting difficulties and probable death. not absolutely necessary to add as a supplement, minimal traces of iodine/iodide can be found in most SSW/NSW; with regular water change, most trace elements wld hv been readily replaced (consumption intake by corals not taken into consideration here). overdosing of iodine/iodide will lead to castrophobic consequences. always better to underdose than to overdose.