sea fishessea fishing

The popular image of a goldfish in a fishbowl is an enduring one. However, some countries have banned the sale of bowls of that type under animal rights legislation due to the risk of stunting, deoxygenation and ammonia/nitrite poisoning in such a small environment.[11] Because of their large oxygen needs and high waste output, the popular goldfish bowls of the past are not appropriate housing for goldfish.[12]

Like most carp, goldfish produce a large amount of waste both in their feces and through their gills, releasing harmful chemicals into the water. This also happens because goldfish, like other cyprinids, lack a stomach and only have an intestinal tract, and thus cannot digest an excess of proteins, unlike most tropical fish.[citation needed] Build-up of this waste to toxic levels can occur in a relatively short period of time, which is often the cause of a goldfish's sudden death. Because of this, goldfish need a large volume of water in which to live. For common and comet varieties, each goldfish should have about 20 gallons(US) or 75 liters of water. Fancy goldfish (which are smaller) should have about 10 gallons(US) or 37.5 liters per goldfish. The amount of 'water surface area' is also important in determining how many goldfish may live in a container, as water surface area determines how much oxygen diffuses and dissolves from the air into the water. A general rule is have one square foot of water surface area for every inch of goldfish length (370 cm²/cm). If the water is being actively aerated by way of a water pump, filter or fountain, a smaller volume of water is needed.