I have had stubborn Tangs before also, as a matter of fact every one has been stubborn but if nori tied to a rock doesn't work put some calerpa tied to a rock, or a clip but mine was even weary of the clip at first. I've found calerpa to be the only thing they'll eat at first........ besides maybe those chips from the wholesaler which was going to be my last and final try but the calerpa has worked every time