i do understand that they are a threat to the wild populations of native species, but.... isn't that only until winter comes and kills them off. in all the information i have gathered, most mfk's are keeping their piranha between 76 and 84 degrees. What is the lowest temperature piranha can tolerate? and where does this line occur across the united states. i know that here in va. piranha are found in the potomac every few years. but they die off every winter. this is just something i had to ask.