We had a one goldfish. It died. The tank sat empty with the filter going for about three months. We got a new fish-just one. We cleaned of the scummy plants and sprayed the rocks with water and put the new fish in with some of the old water and some fresh. The tank is 5 gallons I think.
A month later I was watching the tank and I seen a baby goldfish swimming around! It was hardly bigger than the head of a pin.
We took it out of the tank to keep it from getting eaten and put it in a large vase with water from the original tank. We gave it a large fish flake every couple of days. It is doing great. I came here to find out more about how to care for this tiny creature and now I'm astounded that the thing is alive. We don't have baby goldfish food, an areator, or a heater. i wonder even how the eggs were laid! Is this really weird?