If you had a pet fish as a child, chances are it was housed in a small tank or in a moderately-sized fish bowl. Maybe it was even accompanied by a petite freshwater plant, around which it would swim endlessly. Goldfish can often appear fully content to live within the confines of a glass bowl, especially if it is equipped with a basic aerator and diversified with pebbles and edible plants.
They certainly “can” live in these environments, but the limitations may have severe consequences on their growth, health and longevity. Due to this, we do not recommend keeping goldfish in fish bowls.
Fish welfare concerns, such as the effects of stress due to a lack of space, filtration, and dissolved oxygen, are just as applicable to fish in tanks as they are to fish in farms and marine parks. The well-being of domesticated or farmed fish continues to be a subject of ethical debate.
A fish welfare expert may argue that rearing goldfish in bowls, an environment so different from natural freshwater systems, is abusive, inhumane, and cruel; an aquarium expert might say that bowl-raised fish can live perfectly happy and lengthy lives as long as their basic needs are met. The problem is that not all fish bowls are the same. These spherical tanks have differing volumes, which may be maximized by functional additions in different ways; there are many factors that influence a goldfish’s survival in such an enclosed environment.
A Small Bowl for a Small Fish?
If you’re new to raising goldfish, you may have assumed that small fish can be perfectly housed in a small bowl. After all, they’re “small enough” to swim back and forth, up or down, and in circles within a tight space. You might even consider placing a couple of them in a single bowl because they’re “small enough” to fit. The truth of the matter is that goldfish are likely to grow larger over time, especially if they are purchased as juveniles and are introduced into a large setup.
Compared to permanently tiny freshwater fish like guppies, tetras, and danios, goldfish aren’t actually that small in adulthood. In the wild, they can grow to several inches in length. Those in outdoor ponds tend to match the size of an entire hand. Some varieties become much longer than the diameter of a standard fish bowl!
One of the most common types of goldfish (the type sold in aerated plastic bags in county fairs) can grow up to 12 inches (30 cm) long and live for dozens of years. While a fish bowl is generally believed to “keep them small”, it simply slows their rate of growth instead of arresting it completely. Growth retardation is usually caused by a combination of limitations. It may negatively impact the lifespan of the fish, preventing it from reaching key developmental stages as it matures into an adult.
Nutrient Cycling in a Fish Bowl
Contrary to popular belief, goldfish are high-maintenance. This is due to their capacity to produce large amounts of waste, use up a lot of dissolved oxygen, and pack an appetite that acts up multiple times a day. In fish bowls without a filter or aerator, goldfish may struggle to survive due to suboptimal nutrient cycling rates. Hypothetically, a single goldfish would require about 20 gallons of clean water to survive without supplementary aeration. This makes bowls generally unsuitable for rearing goldfish.
That being said, if it’s truly impossible to house your fish in a larger tank, you may choose to work around the limitations of a fish bowl. If the comfort of your fish is a top priority, consider implementing all of the following guidelines.
- Conduct frequent water changes. Nutrient cycling rates are predictably slower in low-oxygen environments, so toxic ammonia (from fish waste and uneaten food) can quickly accumulate and cause your fish to get sick. Frequent water changes should help reduce ammonia buildup and introduce more oxygen into the system.
- Add a simple aerator and filter. Goldfish bowls can be quite tricky to equip with an aerator or filter due to their shape and size. This is where simple tubes and a small air stone may come in handy. Consider creating an external filter! This should make clean-ups exponentially easier and ensure that fish waste and uneaten food are removed before they can pollute the bowl.
- Do not overfeed your goldfish. Excess feeds are a recipe for poor water conditions in a fish bowl. Although goldfish are known for picking at uneaten feeds (given their insatiable appetites), excess food should be removed. Feed your goldfish an amount that can be consumed within a few minutes. Remove all uneaten particles before they begin to sink. Always veer on the side of underfeeding instead of overfeeding goldfish.
- Do not overpopulate the bowl. It may be tempting to add a companion for your fish. Although it may look as though there is ample physical space for another fish to occupy, an additional fish would do more harm than good. Instead of being a “beloved companion” for the bowl’s original occupant, it would simply reduce oxygen and space.
Naturalizing the Fish Bowl
A great way to increase dissolved oxygen levels, especially in the absence of a proper aerator, is by introducing adequately-sized freshwater plants into the fish bowl. Fully submerged and floating species are also a great means to encourage your goldfish to explore the tank. They’ll add great color to the overall setup. When well-maintained, they should also reduce the chances of toxic nutrient build-up.
Keep in mind that, for freshwater plants to grow properly, they must be exposed to light. If your goldfish bowl is situated in a low-light location, you may need to invest in a grow light. Without one, your plants may not be able to perform their ecological services. Instead, they may die back and use up more oxygen in the process.
Signs of Stress in a Fish Bowl
A goldfish that seems to be swimming in an odd way, turning upside down and bumping into the walls of the bowl, is not attempting to communicate with you in a weirdly cute and quirky way. Odd swimming behavior is usually indicative of a serious problem. It can be caused by a faulty bladder and various diseases, or it can be brought about by poor water conditions.
Other clear signs of fish stress are immobility at the bottom of the bowl, unusually pale coloration, cloudy eyes, and a lack of appetite. Have a water quality test kit on hand so that you can double-check for poor conditions as soon as signs of stress are spotted. If the root cause of stress is not addressed in a timely manner, your fish will quickly deteriorate.
A significant water change may do your fish some good, especially if the bowl is not equipped with an aerator or filter. Better yet, move your fish to a larger, aerated tank and observe for improvements in its well-being.
Final Verdict
When possible, grow your goldfish in larger setups (with filtration and oxygen), or even outdoor ponds, where they can comfortably explore their homes and rest without the risk of rapid ammonia accumulation and oxygen loss. Although fish bowls can be outfitted with tank equipment, their spherical structure prevents the water from cycling efficiently. Even with the help of daily water changes, water conditions may still remain significantly more poor compared to those in your average rectangular tank.
Due to the high risk of premature goldfish death in inadequately-maintained fish bowls, some countries have begun to enforce a ban on them. Belgium, Germany, and Italy, for example, have government-run animal welfare units that highlight the ill effects of fish bowls on the growth and survival of pet fish. They recognize that impulse buys and the use of goldfish as prize items are some of the leading causes of fish bowl sales.
More often than not, goldfish end up in bowls because of a lack of general knowledge of their basic needs and capacity for growth. Though it appears goldfish “can” live in a bowl, it doesn’t mean they should. If you already have one at home, consider moving your fish into a tank – yes, even if it “looks” to be perfectly content in the bowl. If, for whatever reason, a fish bowl is the only option for your fish, carefully observe the guidelines discussed above.
