While goldfish are some of the hardiest creatures in the world, able to withstand an unbelievable amount of neglect and abuse without ill effect, they aren't indestructible. Here's Pool's pro tips for amateur goldfish keepers.
1) DON'T USE CITY WATER STRAIGHT FROM THE TAP Fish don't like chlorinated water. "There isn't any fish in the world that can live in our drinking water," he said. Because of that, Pool recommends using either well water or tap water that has been treated with one of the pet store-available purifying chemicals, then allowed to sit for a day — preferably while being aerated with an air bubbler.
2) YOUR MOTHER WAS RIGHT And wrong. It actually IS possible to feed a goldfish so much that he dies, but he probably won't croak from gluttony. It's the ammonia. "When you pour feed in there, he has to consume it," Pool said. "And then he has to excrete it, and now he's swimming in that ... if [the waste content] gets too high, then the ammonia goes way up in the tank and he's killed by the toxic ammonia." In general, Pool said, goldfish only need to be fed two to three times a week, and then just the barest pinch of food per fish will do.
3) HANDS OFF Like most fish, goldfish are shielded from disease, bacteria and parasites by a protective layer of slime that coats their bodies. If you touch or disturb the fish too much, you can rub off this slimy shield and open him up to infection.
4) CROWDED IS BETTER Unless you want Moby Dick, that is. Crowding goldfish regulates their size. The more space they have to work with, the bigger they'll grow. Keep him in a small bowl, or that inch-long fish you bought from Walmart will wind up resembling a koi instead of a classic goldfish.