Argulus...you mean fish lice? I put the affected fish in a bowl, then hold it such that the part of body with the louse is above water, then with the other hand I press a piece of rock salt I can hold onto the louse. After a while the louse will detach itself and fall into the bowl. I then put the fish back and proceed to torture the louse with more salt until it dies before discarding the bowl of water. This is what I do with mine last time. When I was small though my dad used tweezers which may leave am ark on the fish if not careful.