A Fish Bowl Review:

The good, the bad and the very bad.

Please note: Any of these designs flaws could be overcome by adding an air pump and an in-tank heater.

Also:

1. The size of the fish bowl shouldn’t be too small. If a fish bowl is too small, the volume of water in the bowl will evaporate so quickly you might have difficulties in maintaining water levels.

2. The surface area of the water should be as large as possible. This is because oxygen is transferred from the air into the water through the water surface. If the water surface is too small compared to the volume of water, the oxygen level in the water will become too low. This will either harm your fish or kill them. Aquarium bowl #4 above is an example of a very common yet very poor design.

The very best fish bowl shape would be a shape like #5 where (looking at the water as if it were six sided without the bowl) the surface of the water is larger than the other sides of the water. Its dimensions are 13.4” L X 13.4” W X 9.5” H. To get the volume in gallons, multiply all three numbers by each other and then divide by 231. This means that the volume of tank #5 is 7.38 gallons. That’s an amazingly large fish bowl. Your fish would probably thrive in that fish bowl.

Heating your fish bowl for cheap. What? Really?

Most people don’t consider heating when setting up a fish bowl and yet adding a heater for the sake of the tropical fish is super easy and very inexpensive.

What I recommend is the same type of heater I have for my two gallon square fish bowl. An under the bowl, reptile heating mat. Like this one:

Tap  the  picture  to  view the  price  on   Amazon.

This heating pad keeps my fish bowl a roasty, toasty 78 degrees Fahrenheit (25.5 C). It’s hidden, and it only costs $12 as of this writing.

FYI: The reptile heating pads need to be in full contact with the bottom of the fish bowl to do the job. If this isn’t possible you’ll need to go with an “in the tank” heater.

If you look closely, in the middle of the picture of my 2 gallon, seen through the water, is a black wire coming up from the heater. This heater lays flat underneath (not in) the aquarium bowl.

I have the fish bowl sitting on a nice plastic tray to keep water from splashing on my furniture.

For the last word on fish bowl heating from an expert, read this scientific paper, which basically says that warm water is good for beneficial bacteria (I cover beneficial bacteria in the next section of this paper: Fish Ammonia)

Ammonia In Your Fish Bowl

(or, “How to keep your bowl fish from dying.”)

Fish release ammonia into the water in their urine (yes, fish pee). Ammonia is also a byproduct of decomposition of fish food and plants. Ammonia is toxic to fish and will kill them in a day, maybe two at most.

Your job as a fish keeper is to make sure there is never any ammonia in your fish bowl. It is much, much easier than it sounds.

There are bacteria that love ammonia as their food. They consume ammonia and release nitrite. Nitrite is another chemical that is toxic to fish. Luckily enough, there are bacteria that love nitrite molecules as their food. They consume the nitrite and release nitrate into the aquarium. Nitrate in an aquarium is not harmful to fish.

Thankfully, these beneficial bacteria are just about everywhere. In the air, on inert surfaces, in the bowl of water you give to your dog. You only need one of each bacteria and you’re good to go…kinda.

Even though you only need one of each type of bacteria, they have to have a place to propagate in your fish tank. They also need food (ammonia), and time for the colonies to grow to sufficient size to protect your fish.

For propagation, you will need to add a substrate of some kind to the bottom of your fish bowl. Fish aquarium gravel is best. The bacteria will grow on anything in your aquarium, including the sides, but it needs a “place to call home.” Aquarium gravel is a suitable home.

In my 2 gallon aquarium bowl, I have a layer of black gravel about 1.5 inches thick. The gravel sits on top of a 2 inch thick layer of potting soil (a place for plant roots and beneficial bacteria). So I have about 4.5 inches of substrate that beneficial bacteria can call home. My aquarium bowl is only 8 inches high. This gives you an idea of how important I feel the beneficial bacteria is to maintaining a healthy fish bowl.

The hard part of controlling ammonia in a brand new aquarium bowl: You have to wait about four weeks before putting fish in your bowl. If your aquarium bowl is unheated, you’ll need to wait two additional weeks. The beneficial bacteria will build up during this wait. Because of your patience, your new fish will actually live when you put them in your fish bowl.

You can help the “cycling” process along by adding a tiny pinch of flake fish food to the fish bowl. Doing this every few days will allow the food to decompose and release ammonia to feed the growing beneficial bacteria colony.

Expert Advice:

Nitrifying bacteria, although naturally present in the environment, will take time to accumulate on biofilter media before they can efficiently remove all of the wastes produced by the fish. Setting up a tank and stocking it full of fish the same day, or even within a week or two, is a sure recipe for disaster. The bacteria in the biofilter can require three to eight weeks to cycle (i.e., become established) at 77-80 degrees F; even more time may be required at cooler temperatures https://www.fdacs.gov/Consumer-Resources/Recreation-and-Leisure/Aquarium-Fish/Aquarium-Water-Quality-Nitrogen-Cycle

Cleaning your aquarium bowl

There are two things I do to keep my 2 gallon aquarium bowl clean. Once a week I siphon out half the water using this tool (amazon link).

To remove algae, I use an aquarium magnet cleaner. When using this magnet, it helps that the sides of the bowl are flat. (amazon link)

What type of fish can be kept in a fish bowl?

There are many more fish then these that would do well in a fish bowl. When you’re shopping for fish bowl fish, check the final adult size of the fish you are considering by looking at the sales tags.

A rule of thumb is to place not more than one inch of fish in one gallon of water. I would expand on that and mention that there are small skinny fish and short fish with fat bodies. Take into account the body size of the fish and you should be ok.

Obviously small fish. Here are my top 5 choices (yes, I know, the last two aren’t fish but they are great additions):

There are many more fish then these that would do well in a fish bowl. When you’re shopping for fish bowl fish, check the final adult size of the fish you are considering by looking at the sales tags.

A rule of thumb is to place not more than one inch of fish in one gallon of water. I would expand on that and mention that there are small skinny fish and short fish with fat bodies. Take into account the body size of the fish and you should be ok.

Feeding the fish in your fish bowl

In my opinion, you should only feed flake food to a fish bowl fish (vs frozen foods or tablets). I suggest this because it is easier to control the amount of food you are putting in the bowl, therefore preventing overfeeding the fish or allowing uneaten fish food to rot and create an ammonia spike.

When feeding your fish (or shrimp or snails) you need to consider how big their stomach is. I would say probably as big as this letter: o.

Now that you have a feel for how big a small fish’s stomach is, you can estimate the amount of food to feed them. The keywords are “just a tiny amount.” Another consideration is that if just dropped on the top of the water, those flakes that are eaten by the fish will swell up in the stomachs. Too much swelling food will lead to ruptured internal organs which of course leads to the fish dying.

Feed your fish the tiny amount of food twice a day. To control overfeeding, I would suggest allowing your fish to fast one 24-hour period per week. This will allow the fish to empty its digestive system.

Decorating your fish bowl

Really, the sky’s the limit when decorating your fish bowl. Walk the decorating aisle of your local fish store to get good ideas. Just leave room for the fish!

An interesting idea I came across was to add fairy lights around the aquarium bowl.

Decorating with aquarium plants

My first choice when decorating a fish bowl is adding aquarium plants. They are attractive and provide your fish with oxygen.

Below are some good plants to keep in your fish bowl. These plants need bright indirect light for a while during the day.

Below are 3 plant possibilities for your nano aquarium / fish bowl:

5 tips to keeping a Healthy Fish Bowl

1. Overfeeding your fish will kill them and lead to a stinky bowl. Who wants that? Don’t overfeed your fish.

2. Heat your fish bowl. Heating with a under the bowl reptile heater will keep the fish and the beneficial bacteria healthy and happy. Or you can dress your fish up in tiny winter coats or maybe a small hoodie..

3. Water changes. Change 50% of the fish bowls water at least every month. More often would be better. Clean, fresh water will make your fish happy. In addition, there are nasty bacteria and protozoa that inhabit every tank that will kill your fish (“Fish TB”). These nasties grow more abundant over time. Changing your water will keep those nasties in check.

4. Consider adding an air bubbler (air pump) or a hang on the edge aquarium filter to your fish bowl to increase the dissolved oxygen in the water. Extra oxygen is good for the fish and good for the beneficial bacteria. https://www.fdacs.gov/Consumer-Resources/Recreation-and-Leisure/Aquarium-Fish/Aquarium-Water-Quality-Dissolved-Oxygen

5. Use an aquarium water conditioner that rids your tap water of chlorine and chloramine. I think that all community water companies add ammonia and / or chloramine to their water to kill bacteria. The side effect of these chemicals is that they will kill your beneficial bacteria and your fish.

If you don’t add water conditioner and your fish live, you’ll want to give them a going away party, because they will soon be dead of chlorine poisoning or ammonia poisoning because the ammonia eating (beneficial) bacteria is now dead.

I’ve used this water conditioner for 30 years and can recommend it. (Amazon link)

Additional Reference

Besides the references cited in this article, I also briefly referenced this excellent article:

https://microbewiki.kenyon.edu/index.php/Aquarium_Niche