7 min read

Goldfish Actually Don't Belong In Bowls

For many of us, it's just part of childhood: a goldfish or two in a bowl, purchased on a whim at a pet store.

They're "easy" pets, tiny little things who require only an occasional splash of food and the itty-bittiest amount of space - a circular glass sphere often small enough to fit on a shelf.

Or so we used to think.

Attitudes toward the friendly little fish are changing, and any number of websites will tell you that you shouldn't let your goldfish live in a bowl - in 2004 one Italian town went so far as to ban the bowls altogether.

But why? As it turns out, fishbowls can kill fish.

It's all about water quality, according to Paul R. Bowser, Ph.D., professor emeritus of aquatic animal medicine at Cornell University. "Think of it this way," he tells The Dodo. "The goldfish is living in its own metabolic wastes."

Here's what that means:

Fish poop. A LOT. And they excrete mostly ammonia, which bacteria then convert to nitrite, and which even more bacteria later convert to nitrate. It's a natural process, but the mix of the ammonia and nitrite can reach toxic concentrations in a dirty fishbowl.

And that can kill the fish. For proof, consider that a goldfish in an aquarium could live for 10 or more years, while most fishbowl goldfish would be lucky to make it to 10 months.

Gregory A. Lewbart, VMD, a professor of aquatic animal medicine at North Carolina State University, notes that one of his clients - who keeps her fish in a 1,000-gallon outdoor pond - has fish in their teens and a 30-year-old who just passed away.

"Remember, fish must do everything in the water where they live," he tells The Dodo. "Eat, urinate, defecate, mate, breathe. They can't escape their environment."

Which is why filtration is so important. Bowser recommends a fully equipped aquarium with a bio-filter - commonly placed under the gravel or on the side - that avoids the toxic combination of ammonia and nitrite. Lots of space helps, too, and Lewbart says an aquarium should be no fewer than 29 gallons total for two or three small fish - and a single 3-ounce fish should have at least 10 gallons, if not much more.

With a standard fishbowl, filtration simply isn't possible, and the fish will likely die.

"Unless the person performs very regular and frequent water changes, the concentrations of ammonia and nitrite can increase to toxic concentrations that could kill the fish," Bowser says, noting that fish also do best at normal room temperature.

Of course, there's also the question of whether goldfish in a bowl get sad or distressed living in such a small space.

"If the water quality is not optimal (e.g., high ammonia), I think they would be uncomfortable, and if the conditions were harsh enough, distressed," Lewbart says. "I think they are definitely capable of being distressed/stressed, uncomfortable, and, at some level, could suffer."

Many experts second that, especially as our understanding of fish increases. A 2014 study in Animal Cognition reports that, while scientists cannot definitively state whether any nonhuman vertebrate experiences consciousness in the same way we do, it's likely "that fish perception and cognitive abilities often match or exceed other vertebrates."

Victoria Braithwaite, Ph.D., a professor of fisheries and biology at Penn State, has backed up that notion, once telling Biology News Net that "fish actually are cognitively more competent than we thought before - some species of fish have very sophisticated forms of cognition."

In the end, consider this: Would you want to live your life in one bare room, with only enough space to go in circles? Us, neither. So splurge on that large, filtered aquarium and some lively decor, too.