Judycap, I am amazed that goldfish lived as long as it did. Your nephew must had been doing water change every day. Yes, there are people using daily or even multiple times a day water changes as substitute for an aquarium filter. It can be done on rare occasions, but not recommended due to most people would fail to keep up the water changes of this frequency. A bigger fish tank and an aquarium filter could have saved them all the troubles. With an adequate size fish tank and a sufficient filter, you only need to do partial water change once a week.
It has been said. Goldfish can live for two to three decades if cared for properly. This 12-year-old goldfish is about 40 to 50 years old in human years. It still died young.
To Happyflowerlady, she did not need to put anything in the water. The goldfish did it by itself. In such a small bowl without a filter, a goldfish can quickly poison itself with the toxic ammonia produced by itself. Like I said, I was already amazed by the 12-year mark. Most fish live under such terrible condition usually die within months if not weeks.