I had them (as unhatched eggs)in the water from their native pond for the first few days before gradually "weaning" them into tapwater (in my case, unchlorinated.) The water from the vernal pool had some undesired bug larvae, small beetles and even a few weird looking worm things in it. Now they are in sterile water, and doing good. I decided to use the boiled lettuce because it's human-quality and thus should not give the tads parasites, thus they are parasite free? Or could they have been infected possibly before hatching, which seems unlikely. I figured that since I had them since before they hatched, they should be clean?