Why You Should Never Keep Your Pet Fish in a Bowl

Fish bowls are bad for fish

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You have all the best new technology for yourself, so why are you wasting your time on antiquated bowls for your pet fish? These ancient pet torture devices only make more work for you and cause severe health issues for your fish. Here's why it's best not to use one for your beloved pet.

Why Are Fish Bowls Bad for Fish?

There are many points that make bowls a poor choice for a fish pet. Yes, they may be easy to set up, but if you want to keep your fish healthy and happy, that's where the convenience stops. The following information will explain why keeping your fish in a bowl is bad for its health.

Lack of Nitrogen Cycling

The process of converting the primary fish waste of ammonia into its less toxic component, nitrate, requires a place for beneficial bacterial to grow. Usually, this is accomplished by a standard aquarium filter. Bacteria can also grow in the aquarium substrate, which many bowls have, but the bacteria requires aeration through water movement, which bowls lack due to not using any filtration. The bacteria in the substrate in a fish bowl does not get oxygen and the ammonia waste excreted by the fish does not pass through the gravel if there is no aeration or water flow, so the ammonia builds up. If the fish waste isn't removed, it will cause the fish to die.

pH Swings

Fish living in bowls are often subjected to extreme changes in water quality. This usually involves setting your fish aside in a small cup while performing a water change and cleaning the fish bowl. The biggest risk in doing this is a sudden swing in the water pH (acid-base balance). Water in a fish bowl will slowly use up its buffering capacity (carbonate hardness or kH) as your fish breathes and metabolizes the food. Once the kH is decreased, the pH will start to drop.

A sudden, heavy water change will then shoot this pH back to "normal" or tap water level. This can cause serious health issues and even death for your fish if they are not able to compensate for this sudden change in pH. With any aquarium or fish bowl, frequent partial water changes are necessary to remove wastes in the water and replenish the minerals that balance and buffer the pH.

Lack of Oxygen

Fish need oxygen. Another great feature of filters is that they are constantly adding oxygen to your aquarium through aeration. Yes, there is some oxygen absorption that occurs at the air-water interface, but in most instances if the water is not moving, relatively active fish will use up the oxygen faster than it can be replenished. You can drop in a small aerator, but many of these are too strong for most tiny bowls and can create currents fish have to constantly battle against. It is better to keep your fish in an aerated aquarium where the oxygen content in the water is consistent.

Inconsistent Temperature

Bowls are very small, making the water very susceptible to varying environmental temperatures. A bowl kept in the sun versus shade will vary widely in temperature. Most small bowls do not have room for an aquarium heater, so there is no way to keep the water consistently at the proper temperature. This can be a problem for temperate fish and is a severe problem for tropical fish that require warm water temperature year around, such as bettas.

The Elevator Scenario

In order to best illustrate the environment of a bowl, consider if you lived in an elevator. You have a clean space in which to live to start, and every once in awhile, food is dropped in the top. But you have no where to put your waste, limited space to explore, and a certain limit of oxygen. After time, the waste builds up, there's no where to put it or move it out to, and your oxygen starts to dwindle.

Suddenly, the elevator doors open, fresh air rushes in, causing you to get a little lightheaded, and the cleaning crew comes and does their thing. Sure, you'd manage to survive in this environment, provided you don't jump out of it, which some fish attempt to do, but you'd be far from thriving. Wouldn't you rather live in a house with air conditioning, heat and ventilation, and proper plumbing? Guess what? So would your fish.

How to Upgrade to a Properly Filtered Aquarium

So you've decided to join the healthy fish party. Congratulations! Before you go dumping your fish from his bowl into a new tank, be sure to assess the following points:

New Fish Acclimation

When adding new fish to any aquarium, it is critical to acclimate them properly. This goes for tank upgrades too! Most often, you will not be bringing any of your fish's bowl water with them into their new tank, so be sure your fish is properly acclimated to their new aquarium's water pH and temperature before dumping them in!

New Tank Syndrome

Any new aquarium will undergo "New Tank Syndrome," where new bacterial colonies are established to perform the nitrogen cycle: converting Ammonia to Nitrite then to Nitrate. Yes, those products on the pet store shelves say they will "instantly" start your nitrogen cycle, but they won't. They may add certain bacteria species that help with the break-down of fish wastes and may speed up the nitrogen cycle to only a few weeks, but they don't instantly add the amount of beneficial bacteria needed for an aquarium already full of fish.

The best method for cycling a new aquarium is starting with a low bioload of fish and slowly adding a few fish at a time over 4-6 weeks, until you have added the proper amount of fish for your aquarium size. We know this takes away the instant gratification, but a bowl upgrade usually has limited participants anyway. Adding too many fish too quickly will cause an ammonia spike that may kill all the fish!

You will see spikes of ammonia, nitrite and finally nitrate as the tank is "cycled." Buy a test kit and make sure their levels do not get high enough to harm your fish. If they are too high, do a water change. It will take 4-6 weeks to complete this transition.

Environmental Adjustments

If your fish have spent their life in a bowl, they are completely naïve about the wonders of a properly filtered aquarium. Do not be surprised if they hide and disappear for a few days. Once they get used to their new environment, they will start to come out and explore. It is a great idea to provide additional hiding places in new environments so your fish feel safe.