I'm considering adding a puffer to my semi-aggressive FOWLR 180 gallon aquarium. I read that parts of it's flesh are poisonous. I would like to know if a puffer dies will it wipe out all the fish in my tank? IF they get get stressed do they release any toxins? Basically is there any threat to my existing fish from adding a puffer to my aquarium because of their poisonous flesh and toxins?