Because goldfish can be kept easily in small ponds and aquariums, they make good pets, but like many other pets, they must have proper care and the right kind of place to live.
A two inch fish requires a minimum of two gallon of water containing sufficient oxygen to support life. Some oxygen will make its way into the water of an aquarium from the air that touches the surface. Plants in an aquarium also help furnish oxygen. Snails help keep an aquarium clean. Thus, with plenty of plants and snail, the water in an aquarium does not have to be a quite unsuitable abode for goldfish.
It is important that goldfish should not be overfed. They can be fed such things as dried insects in addition to commercially prepared goldfish food, but they should never be fed more than once a day. Even then, they should not be given more food then can be consumed in about five minutes. This ensures prolonged life.
Which of the following helps supply goldfish with oxygen?