Goldfish bowls are a staple at department stores as well as many pet shops. Ask anyone who had a goldfish as a kid and likely they kept it in a goldfish bowl. Google for Goldfish bowl photos and you’ll find thousands of them in a variety of shapes. Obviously Goldfish bowls must be the ideal home for a goldfish, right? Wrong!
Goldfish bowls are far too small for even a single Goldfish. Although the Goldfish you buy at the store looks small, it's only a matter of time before it outgrows the Goldfish bowl. If properly cared for even a small Goldfish can easily grow to a half foot in length, and many will grow larger than that.
Furthermore, Goldfish bowls are too small to accommodate a filtration system, or equipment to circulate and aerate the water. As a result, the water will quickly become depleted of oxygen, and accumulate toxins that are dangerous to the fish. With such a small quantity of water, it doesn't take long to hit the danger zone.
Too Much Waste
Goldfish are robust fish that produce more waste than similarly sized tropical fish, which presents a huge challenge in a Goldfish bowl. With no filter or beneficial bacterial colonies, the only way to remove waste and its by-products is to frequently change the water. And I do mean frequently, not just now and then.
Although water changes are good, performing them daily is stressful for the fish. Most owners tire of the constant work and tend to go longer and longer between water changes. If the fish appears healthy, the owner may let water changes slide for weeks or months. Under such circumstances it is likely that the fish will soon die from ammonia or nitrite poisoning. Even if the fish doesn’t die, it will become more susceptible to disease. No Goldfish kept in a Goldfish bowl lives as long or is as healthy as one kept in the properly-sized and filtered aquarium. Some tough Goldfish may survive in such circumstances for a few years, but that is far from a normal lifespan for a Goldfish, which can be thirty years or more!
What Goldfish Need
Goldfish should be kept in an aquarium that is equipped with a filter. The tank should be large enough to accommodate an adult Goldfish, which can be anywhere from a half a foot to well over a foot in length. Steer clear of mini aquariums, even if they show a photo of Goldfish on the front. That photo is simply marketing, and not a true endorsement of the tank.
The smallest size tank to consider for a Goldfish is twenty gallons. If you want to keep several, you’ll need a larger tank. Filtration is a must, and should have a water flow of at least four times the tank size, in gallons per hour. For example, a twenty gallon tank should have a filter with a minimum capacity of 80 gallons per hour (gph). In this case more is better, so don’t hesitate to get a more powerful filter.
A heater is not needed, as Goldfish prefer cooler water. However, it’s wise to equip the aquarium with a thermometer so you can monitor the water temperature. As water temperature rises, the amount of dissolved oxygen drops, which can prove harmful, or lethal, to your Goldfish. Live plants help remove wastes, so if possible, decorate your aquarium with live plants rather than using artificial plants.
With a proper size aquarium, good filtration and care, your Goldfish can live for decades. Do them a favor and just say "no" to the Goldfish bowl.