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Keeping a Fish Bowl

(and small tanks, vases, urns, or buckets)

(The First Tank Guide)

Contrary to popular opinion, fish bowls and vases are NOT easy to care for. In fact, it becomes easier to care for aquatic pets the larger the environment (tank or bowl) you keep them in. However, other factors play a part in how much water you can keep in a bowl...

Remember, any container under ten gallons, whether it is sold as a "tank" or as a "bowl," and whether it is filtered or not, is small enough that it should be treated as a small tank or bowl. Also, any tank that is not filtered, regardless of its size, should be treated as a small tank or bowl.

If you choose to keep fish in a bowl, there are several things you should keep in mind. Fish kept in bowl will continue to produce waste as they consume food, and any excess food that gets into their tank will still begin to decay. Decaying food, fish waste, and debris that falls into the tank from the air will all contribute to poor water quality, and can eventually reach toxic levels. In a small environment like a bowl, this problem is compounded by the small volume of the water. In larger environments, there is more water to dissipate these toxins.

Keep the water in your fish bowl low. The water level should be near the widest part of the bowl to optimize the surface area where Carbon Dioxide can be released into the atmosphere and Oxygen can be dissolved into the water. Remember that lowering the water level also decreases the water volume in the bowl, thereby decreasing the ability of the water to dissipate fish waste and other toxins and lowering the fish capacity of the bowl.

Basic Fish Bowl Maintenance

Fish bowls require a great deal more maintenance and harder work than larger aquariums. Ideally you'll want to change 50-100% of the water in your fish bowl or small aquarium every day or every other day to prevent the tank from becoming toxic.


Feed your fish sparingly. The most common reasons for premature fish death in the hobby are over feeding and inadequate maintenance. Feed your fish only once a day, and in a bowl, only what they COMPLETELY consume in under a minute. Excess food in the bowl will begin to decay, and in the limited capacity of a bowl, the water can become toxic rapidly. Feed your fish a variety of quality fish foods—feeding only one food presents the possibility of a vitamin or mineral deficiency, and the number of quality foods available on the market today allows every pet owner to provide a selection of high quality foods for their fish.

Fish Bowl Capacity

Possibly the most frustrating thing about owning a fish bowl is the limited capacity for fish. In a filtered bowl, we recommend keeping only 1" of fish for every 1.5-2 gallons of water in the bowl—remember that the bowl is probably holding substantially less water than its total capacity since you are keeping the water level lowered to the widest part of the bowl—usually 1/3-1/2 of the bowl's capacity is air, not water. If you are not filtering your bowl, we recommend keeping your population at 1" of fish for every 3 gallons of water or lower. Remember that a fish's size is not determined by the environment it is kept in, but rather is controlled by genetics. The small fish you purchase for your bowl today may be a very large fish by the time it is mature. Keeping a fish in an environment that is too crowded or too small is cruel and can lead to a wide variety of health problems from reduced immune systems to crippling skeletal deformities or failure of internal systems.


Diligent maintenance of a bowl, monitoring your fish for problems and addressing them as soon as they arise, and insuring that your bowl provides sufficient space for your fish can provide an environment where your fish can remain healthy for years. Though a larger environment is always healthier and less work, a well-cared for bowl can be an attractive accent to any home or office.

Always remember that the only real solution to keeping your fish healthy and happy will be upgrading to an appropriate sized tank of at least ten gallons with the necessary equipment to properly care for your fish.

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