So when the girls wanted goldfish for pets, I said they could.. They picked out six of them and were excited to bring them home.... Excitement ran out when they discovered that the fish bowl would be a stock tank!   (Not like they would be cleaning it anyway)..   The fish are thriving and we have lost none of them.  We do not feed them, they live of the green growth and all the feed that dribbles from the livestock when they drink water.  We put in tank heater under the float to keep it from freezing and when they get too cold they hang out by that.