 Not to worry, though, our fish may have benadryl in it. Because so many drugs are excreted in our urine, when we pee them down the toilet, they can end up polluting our rivers and streams and the flesh of the fish swimming in them. In fish fillets, they found benadryl, cardazim, tegrita, lopid, zoloft, and prozac metabolites. The levels they found were really low, but what if these compounds bioaccumulate in tissue or have unintended consequences from the complex mixtures of contaminants we're exposed to?