This post may contain affiliate links.
A no-filter fish bowl is not easy to care for. It takes a lot of work and dedication to maintain unfiltered fish bowls.
To keep fish bowls clean without a filter, do massive water changes, preferably 30-50% on alternate days. In addition to that, don’t overfeed your fish, clean gravel once a week to remove trapped food particles and feces, and introduce live plants in the habitat to manage nitrogenous waste.
Making fish thrive in a fish bowl without a filter is quite a task. How you can do it efficiently is what we are going to discuss in the following sections.
How to Keep a No-Filter Fish Bowl Clean?
A fish bowl without a filter puts the inhabitants at risk of ammonia poisoning.
Organic matter, such as uneaten food and fish poop, when it stays longer in the tank and decomposes, it produces ammonia. Besides, fish also excrete ammonia through the gills, with relatively little being lost through urine and feces.
Since a fish bowl has no means of mechanical and biological filtration, the only way to get rid of organic waste and deadly ammonia is through daily water changes.
To regulate feedings, cleaning the gravel and adding aquatic plants are additional practices to prevent the water from deteriorating and keep the fish bowl clean.
Perform Daily Water Changes
Water changes remove the solid waste and ammonia, making the bowl habitable for fish. As you introduce fresh water, it dilutes any available dissolved compounds that could be stressful to fish.
For fish bowls without a filter, it’s recommended to carry out 30 to 50% water changes every 2 days.
The smaller the fish tank, the quicker ammonia levels go up. Therefore, the only way to keep the toxic ammonia under control is frequent and massive water changes.
Aren’t Big Water Changes Stressful to Fish?
Water changes, as huge as 50%, can cause fluctuations in the water parameters and is a stressor in itself.
However, the stress of massive water changes is less problematic for fish than burning their gills swimming in high-ammonia water.
Before adding fresh water to the bowl, always match the water parameters, mainly pH and temperature. It helps reduce fish stress.
If you use dechlorinated tap water, it is best to leave it exposed to air overnight before introducing it to your fish.
Don’t Overfeed Your Fish
Always feed your fish according to their appetite and size. Or, as a rule of thumb, only offer the amount of food they can consume within one minute. In a filterless bowl, it’s better to underfeed your fish than overfeed.
Overfeeding often results in uneaten food and a lot of poop. A no-filter fish bowl will quickly become a mess if you don’t control how much food you give. It will not only deteriorate the water quality but also increase the cleaning work for you.
After every meal, take a close look at your fish bowl, and if you find any leftover food floating over the surface, scoop it out.
Keep the Gravel Clean
While water changes are effective in removing most of the waste, dirty gravel can quickly contaminate freshwater, making your efforts go in vain.
Aquarium gravel can trap uneaten food, fish poop, shed scales, dead bits of plants, and other debris, which, if not cleaned, will start to rot and affect the water quality.
For a fish bowl, at least once a week, you should stir the gravel and vacuum it to remove much of the gunk accumulated at the bottom.
Add Live Plants
Adding aquatic plants not only makes your fish bowl look beautiful but also helps reduce nitrates – a byproduct of ammonia.
Now, many of you might be wondering if you are going to need nutrient-rich substrate for the plants. Not for the low-demanding plants – as they can live off the fish waste and other nutrients in the fish tank.
Any gravel or substrate that is good enough for the plants to help root down in the tank, will work.
Hornwort is a popular low-light aquatic plant you can choose for your fish bowl. It’s readily available at local fish stores, so go today and pick up a few Sprigs of Hornwort.
How To Oxygenate a Fish bowl Without a Filter?
Apart from removing the debris from an aquarium, a filter’s role is to oxygenate the water by increasing water movement. A habitat with stagnant water and no surface agitation can’t remain oxygenated.
So when you have a fish bowl with no filter, you will need to find a way to keep the water aerated.
Probably the most efficient and hassle-free way is to install a USB-powered air pump. They are small in size and don’t require much space.
You can also DIY an air pump at home. For that, check out the videos on Youtube, as there are many of them.
Other methods to increase oxygen levels in aquariums include large water changes, manually stirring the water, placing a fan near the aquarium, and pouring freshwater water from a height during water changes.
Do live plants help?
Many wonders if they can use live plants to introduce oxygen in their no-filter fish bowls.
The truth is, plants can’t produce enough oxygen to compensate for the lack of water circulation or agitation in tanks.
Let me explain why?
Plants don’t produce oxygen at night but rather uptake oxygen from the water by competing with fish.
So even if you have enough plants to provide oxygen during the day, your fish will still suffocate when the lights go out.
If you are thinking of keeping your fish bowl lights open at night, don’t do that unless you want to encourage algae growth.
You should definitely have plants in your tank, but don’t count on them for oxygenation, at least not at night.
Can Fish Live in a bowl Without Filter?
They say keeping fish in bowls is cruel.
Firstly, fish bowls don’t have filtration. And if you aren’t performing frequent water changes, you are making your fish soak in a septic tank collecting feces and urine.
A habitat as small as a fishbowl is also at risk of ammonia poisoning.
Secondly, keeping fish in an inadequately sized space stunts their growth, decreases life expectancy, and can cause bodily deformities and diseases. In worst-case scenarios, it can lead to premature death.
Scientific evidence suggests that fish can feel pain, fear, and psychological stress. They aren’t as happy in small containers as in larger ones.
These lovely, tiny, intelligent aquatic animals shouldn’t be merely surviving but thriving.
The bottom line is: just because you can keep a fish in a cruelly small bowl doesn’t mean you should.
Which Fish Are Suitable for No-filter Bowls?
When choosing fish to keep in a filterless and heaterless bowl, look for the following qualities:
- Hardy Fish: These fishes can handle sudden changes in their surrounding. They can quickly adapt to a wide range of water parameters, therefore, are easy to maintain in fishbowls where the habitat can become toxic very quickly.
- Small Fish: Takes less space and are best to utilize the limited area in a bowl.
- Cold Water Fish: Unlike tropical fish, cold water fish doesn’t require their tanks to be heated. Most fish are adaptable to different temperature limits if kept constant without many fluctuations.
- Avoid Pooping Machines: Given the size of a fishbowl, you should stay away from waste-producing fish species. They will quickly ruin the water quality, thus increasing the frequency you change the water and clean the fishbowl.
Hardy fishes that can live without a filter and are easy to take care of include:
- White cloud minnows
- Blind cave tetra
- Salt and pepper corydoras
- Zebra danios
- Ember tetra
- Pea pufferfish
- Six-ray corydoras
- Scarlet badis
Can we cover up the fish bowl?
Securing a lid over a fish bowl prevent the water from evaporating and keeps dust and flies out. However, it shouldn’t be sealed and have air passages.
Can a goldfish live in a no-filter bowl?
Goldfish are perhaps the worst choice for a bowl or any small container without filtration. Why? Because they eat a lot and as a result produce a heavy bioload.
Is it safe to do 100% water change in a fishbowl?
Changing 100% water can be stressful for your fish. However, occasionally, you can do it, such as during tank maintenance. But make sure to match the pH and temperature to help reduce the shock.
For no-filter fish bowls, does an air pump necessary?
Labyrinth fish – ones that possess the ability to breathe air from the surface – such as bettas, can live without an air pump. To keep non-air-gulping fish alive, you must keep the water oxygenated.
How to know if your fish bowl has low oxygen levels?
Common signs that indicate a lack of oxygen include – fish gasping on the surface, labored breathing, rapid gill movements, moving around less, and reduced appetite.
Keeping fish healthy in a no-filter fish bowl is not an easy task.
Hobbyists must perform frequent water changes, feed less, and clean the entire bowl and its contents at least once a week.
If you can do it, nothing stops you from maintaining a healthy, clean fish bowl.