False doctrine?

Tonight I was putting the girls to bed and was frustrated because it was taking them a very long time to go to sleep (thanks to Daylight Savings) and I told them it was their last chance to go to sleep before I took their dolls away. Paris then piped up with "We need to make the right choice or Joseph Smith will send a big fish to eat us up." That took me a little off guard, but I told her that wasn't quite true and she insisted that "if you make wrong choices, Joseph Smith sends the big fish to eat you up." I asked her why she thought that and she said that's what she learned in Primary today! I'm guessing I just have a 3 year old that wasn't paying very close attention in class!