let's put it like this.. I really want to "date" Jessica Alba... do you think that will happen?
nah.. jk.. sort of.. first, the snakehead would outgrow and then eat the jar, otherwise if you are lucky and get one of the sociable snakeheads the jar will probably turn homicidal when about 8" and try to mess with the snakehead who will respond by totally and utterly mutilating the jar beyond all ability of understanding if he is not a total wuss..
second scenario. you hit jackpot (about the same odds) and they live happily ever after in your 400+ gallon tank that you have cykled and ready!