A filter is unnecessary for fish that are not in need of one. Every fish needs a filter. It is the only thing that can replace it. When I was asked to write this article, I had to face a moral dilemma. My initial reaction was “No.” It is unethical to create content about a topic such as this.
After recollecting myself, I realized that not everyone has a filter at all. It can sometimes break down or lose its function. Sometimes, it can go out of function.
Yes, you can keep fish without a filter. But only for a short time. All fish are not created equal. Some fish are more resilient than others.
Certain fish species can survive without the use of a filter if they are given the right conditions, such as water changes and strategically placing plants.
Some of these are:
- Bettas (Betta splendens)
- Zebra Danios (Danio rerio)
- Guppies (Poecilia reticulata)
- Ember Tetras (Hyphessobrycon amandae)
- White Cloud Minnows (Tanichthys albonubes)
- Sparkling Gouramis (Trichopsis pumila)
- Pygmy Corydoras (Corydoras pygmaeus)
- Dwarf Puffer Fish, Carinotetraodon Travancoricus
- Scarlet Badis (Dario dario)
- Six-Ray Corydoras (Aspidoras pauciradiatus)
- Endler’s Livebearers, (Poecilia wingsei)
These fish are some of the most difficult fish in the hobby. They are very patient and will forgive beginners who make mistakes like taking too long to set up a filter.
These are some of the things you should consider when selecting fish that can be left without a filter for a while.
Choose Hardy Fish
This is easy to understand. Tanks that do not have filters are more likely to be polluted rapidly. This will lead to a greater number of toxic compounds such as ammonia or nitrite being accumulated.
You must therefore choose fish that are genetically sound and ‘built strong’. These fish, such as jellybean cichlids or fancy goldfish, would be more vulnerable to a filterless aquarium because of their genetic problems.
Choose Small Fish
Small fish means small bioload. A smaller bioload equals less pollution. If you kept goldfish in a tank without filters, it would be impossible to kill them. Goldfish are the turtles of fish world. They poop quite a bit.
Smaller fish naturally have smaller appetites and excrete fewer waste. The water parameters will be more stable for longer periods of time.
Choose Solitary Fish
Again, more fish equals more bioload. There will be more waste if there are many fish in the tank. Your tank will have more food waste and poop, making it susceptible to sudden spikes in ammonia.
Fish that are exposed to high levels of ammonia will become suffocated and have their bodily functions disrupted. Reddened gills and labored breathing are some of the signs of ammonia poisoning.
It is important to choose fish that are able to live alone. You can make fish anxious and stressed by keeping them alone in a tank without filtering. This will cause their health problems.
Choose Coldwater Fish
Some of the fish in the above list aren’t coldwater fish. This is why I added this tip. A lack of filtration can lead to more frequent water changes. Rapid temperature fluctuations can be caused by frequent water changes.
The ability to handle temperature changes is naturally greater in coldwater fish than it is for tropical or saltwater fish.
However, I do hope you don’t keep fish without a heater and a filter.
Let’s first discuss the characteristics and general needs of the fish we have just mentioned. Next, let us find out why filters are so important – and even essential – for your fish.
Why Do Fish Need Filters?
Fish need filters for the same reason that good air is essential for us. Filters will remove the debris, prevent toxic buildups of ammonia or nitrates, and oxygenate water. It is essential that you install a filter if you don’t want your fish to become flies.
It Breaks Down Ammonia
No matter how tough your fish are, ammonia can be fatal to them. When organic matter and food are discarded, ammonia forms in closed systems like fish tanks.
This harmful compound can suffocate fish and burn their skin. It can also cause internal organ damage and gill irritation.
It is therefore essential to have a filtration system that can break down ammonia and make it into less harmful compounds.
Live plants can be added to an aquarium to help them consume ammonia. The plants will only need to consume what they really need.
You might be able to save your fish from ammonia poisoning if you have a large tank that is only stocked with a few fish. This is still unlikely.
Filters contain biological media that allows good bacteria colonies to thrive and live in the filter. These tiny organisms work together to convert harmful ammonia into less harmful compounds.
It Gets Rid Of Algae
Your fish tank water must be kept moving. The water that becomes stagnant can become a breeding ground of algae.
Water flow will not be possible if there is no filtration system. Algae will thrive in this environment. Algae in aquariums are not only unsightly but also a sign of an imbalance and high levels pollutant levels.
It can also have many negative consequences. It can steal nutrients from your plants, increase the pH of the tank, trap fish, and even starve it at night.
It Supports Plants Growth
As you know, plants require a variety of micro- and macronutrients in order to grow properly. The water column is the main source of these essential nutrients in an aquarium.
Without a proper filter, water won’t circulate throughout the tank. The plants won’t get the nutrients they need if the water isn’t circulated.
Your plants will need to compete directly with the algae to get any nutrition from the tank.
We can therefore conclude that filters are not only crucial for fish, but are also vital for plants.
It Doesn’t Stress The Fish
You will notice a difference in the frequency of water changes and deep cleanings if your tank doesn’t have a filter.
Your poor fish will be shaken to the core by being netted and then transferred to another water source.
This is because, no matter how tough the fish are, they don’t like sudden or frequent changes in their environment.
When stressed, the body of a fish can stop producing white blood cells. This lowers its immunity and exposes it to many pathogens.
A sound filtration system is essential in that the fish won’t be as stressed as they would in a non-filtered environment. The fish will naturally be happier and less stressed.
Maintenance Will Be Easy
Maintenance-free filtration systems are far from possible. If you allow debris to collect in the mechanical filter it will turn into ammonia, negating its primary purpose.
A filter can also help you save time and effort. You won’t have to constantly be checking the water parameters.
Water tests and water changes will be less frequent, which will save you time and effort over the long-term.
A Breakdown Of A Filter’s Functions
Today, filters come with all three types of filtration systems: mechanical, chemical, or biological.
Biological Filtration
Biofilters are used to remove poisonous ammonia from fish waste and leftover food. All tanks require biological filtration. This is the most cost-effective and efficient way to get rid of toxic ammonia.
Mechanical Filtration
Mechanical filtration captures small particles of waste like leaves from plants and leftover food. They are then removed from the tank and allowed to decompose, producing ammonia.
Chemical Filtration
Chemical filtrations such as zeolite or activated carbon are used to remove heavy metals and dissolved organics by using chemistry (for instance, “ion exchange resins” and “adsorption).
Chemical filtrations are best suited for short-term problems such as removing chemicals and medications after they have served their purpose, or purifying tap water.
Science has made it possible for filters to be fully equipped with all three types of filtration systems in order to maintain your tank’s water parameters.
Our Filter Recommendation
For most of our fish tanks, we use the Marineland Penguin Bio-Wheel Power filter at Urban Fishkeeping.
After reading dozens upon dozens of Amazon reviews, I decided to purchase this product.
Take a look at the bells and whistles in this aquarium filter.
- Multistage filtration systems provide chemical, biological, as well as mechanical filtration.
- The patent-pending Bio-Wheel technology allows for wet/dry biological filtering
- Available in 5 sizes that are suitable for all aquarium types
- Removes waste, odors and discoloration effectively
Let’s take a closer look at these tough fish.
Bettas (Betta splendens)
| Size | 3 Inches |
| Lifespan | 3-5 years |
| Care Level | Medium |
| Water Temperature | 76-81 degrees F |
| pH | 6.5-7.5 |
| Behaviour | Semi-Aggressive |
You would think a fish as beautiful as a betta is delicate. The opposite is true. Bettas are renowned for their distinctive tails and bright colors. They are one of the most hardy fish in the hobby.
Bettas are also carnivores. They are fond of meaty foods. You can feed them pellets with protein, or freeze-dried and live foods. Bettas will eat insects and larvae in their natural environment.
Bettas are known as Siamese Fighting Fish and they live up to their name. These fish are very aggressive, especially the males. They will fight their reflections.
It is possible to have a sorority with female bettas. However, it is not a good idea to keep two male bettas in one tank.
Although bettas love to live alone, ghost shrimps and mystery snails, catfish and loaches make great tankmates.
Zebra Danios (Danio rerio)
| Size | 2 Inches |
| Lifespan | Maximum 5 years |
| Care Level | Simple |
| Water Temperature | 64-74 degrees F |
| pH | 6.5-7.0 |
| Behaviour | Peaceful |
Zebra danios are South Asian natives and are known for their distinctive purple stripes. The most impressive thing about these fish is not only their ability to survive fast-moving streams, but also their ability to thrive in stagnant water.
Zebra danios are omnivores. They are easy to care for. They can be fed pellets, flakes or blanched vegetables, as well as live and frozen invertebrates.
Zebra danios tend to be social and peaceful. They love living in large groups, as schooling fish. You should aim to keep at most 6 together.
Zebra danios can become very stressed if they are left alone or in small groups. The zebra danios will then resort to biting their fins.
A danios tank would be well-suited for fish like gouramis, loaches, barbs and swordtails. They can nip fins so make sure they are not paired with angelfish or bettas.
Guppies (Poeciliareticulata).
| Size | 0.6 to 2.4 Inches |
| Lifespan | Maximum 2 years |
| Care Level | Super Easy |
| Water Temperature | 75-82 degrees F |
| pH | 5.5-8.5 |
| Behaviour | Peaceful |
Guppies are, in my opinion, one of the most overlooked fish in the hobby. Guppies are more than just a feeder fish.
Male guppies are able to be seen in bright colors while females can look a bit duller and more drab. Both sexes are active swimmers and love to swim around in the tank.
Guppies are an omnivore and one of the easiest fish for you to feed. Guppies will eat whatever you give them. You can supplement their food with staple pellets and flakes or add yum snacks such as peas, bloodworms and shrimp to their diet every once in a while.
Guppies are a very well-mannered fish. Guppies are very active swimmers who enjoy being with their own species. They find safety in groups.
To impress potential partners, the male will perform a funny fin-wiggle to attract them during mating season.
Guppies are best paired with platies, ghost shrimps, and gouramis.
Ember Tetras (Hyphessobrycon amandae)
| Size | 3 Inches |
| Lifespan | 2 to 4 Years |
| Care Level | Simple |
| Water Temperature | 73-84 degrees F |
| pH | 5.0-7.0 |
| Behaviour | Peaceful |
The fascinating Ember Tetras are as captivating as their namesake. Their bright orange-red color is accentuated by a gradient pattern. They live in the Araguaia River’s slow-moving waters, which are often surrounded by dense overhanging vegetation.
Like danios, ember tetras are omnivores as well. It is easy to feed them. There are many options. You can give your pet a variety of food options, including pellets and flakes.
They enjoy nibbling on aquarium plants every once in a while but pose no danger.
Ember tetras can swim well. They need lots of open space to swim in. You will also need to plant some plants to provide them with hiding places to retreat to.
These fish are calm and active, and won’t fight with other tank members.
Your amber tetras will be able to live with small rasboras and neon tetras as well as red cherry shrimp, dwarf gourami, dwarf gourami, and pigmy catfish.
Tetras love to nibble on fins and should not be kept with fish that have flowing fins.
Avoid keeping them with aggressive, large fish.
White Cloud Minnows (Tanichthys albonubes)
| Size | 1.5 Inches |
| Lifespan | 5-7 years |
| Care Level | Simple |
| Water Temperature | 64-72 degrees F |
| pH | 6.0-8.0 |
| Behaviour | Peaceful |
White cloud minnows stand out from other species due to their metallic bodies and bright red tail. Their beautiful iridescent scales are surrounded by black lateral stripes.
White cloud minnows can eat almost anything and they don’t care what you put in your mouth. They are actually micro predators in the wild. You can also give them microworms and mosquito larvae, as well as blanched vegetables, dried pellets, frozen food, and algae to keep them occupied in your tank.
White cloud minnows, like all members of the minnow family have a strong schooling instinct. You should aim to keep at most 5 minnows together.
They are quiet and peaceful most of the time, but can be very mean and aggressive when they get married.
Sparkling Gouramis (Trichopsis pumila)
| Size | 1.5 Inches |
| Lifespan | 4-5 years |
| Care Level | Simple |
| Water Temperature | 75-82 degrees F |
| pH | 6.-7.0 |
| Behaviour | Peaceful |
When describing sparkling gouramis, beautiful would be an understatement. They look like iridescent, shiny bullets that dart through the tank’s water. They stand out in fish tanks thanks to their blue, green, and red sparkles.
Sparkling gouramis can be considered omnivores. In the wild, they eat primarily insects, worms and zooplankton. They also require a high-protein diet in the tank.
You can give them live daphnia or bloodworms as well as artemia flakes and vegetable flakes.
These fish were originally drawn from waters surrounded by dense vegetation. They would stick to the planted areas of the fish tank.
Although they can seem aloof and anxious when first exposed to a new environment for the first time, once they feel comfortable they become curious.
Dwarf suckers, dwarf gouramis and dwarf pencil fish are all suitable tank mates for sparkling uramis. However, they shouldn’t be paired with big, aggressive fish.
Pygmy Corydoras (Corydoras pygmaeus)
| Size | 1.2 Inches |
| Lifespan | Maximum 3 Years |
| Care Level | Simple |
| Water Temperature | 72-79 degrees F |
| pH | 6.4-7.4 |
| Behaviour | Peaceful |
Pygmy corydoras, also known as pygmy catsfish, are often called pygmy corydoras. They are the smallest of the catfish species, measuring in at 1.2 inches.
These fish display striking black and white patterns that can be difficult to identify due to their slim physique.
The wild pygmy corydoras are mainly a scavenger at the bottom.
You can also give them sinking pellets. You can add brine shrimp, insect larvae and bloodworms to their diet, as they are omnivores.
These fish have a calm temperament and are very tolerant of other fish in their tank. The ideal tankmates of pygmy cats would be mollies and neon tetras as well as dwarf gouramis, cherry barbs and zebrafish.
Dwarf Pufferfish, Carinotetraodon Travancoricus
| Size | 1.4 Inches |
| Lifespan | Maximum 4 years |
| Care Level | Medium |
| Water Temperature | 74-82 degrees F |
| pH | 6.5-8.5 |
| Behaviour | Territorial |
Dwarf pufferfish are one of the most beloved and loved pufferfish species. They are a tropical freshwater fish that is so captivating because of their large eyes and small stature.
Although they may seem small, wild animals are hunters. In their natural habitat, they eat mostly algae, copepods and insects.
You can also give them staple pellets or flakes.
These fish prefer to live a quiet life. They can live peacefully with other peaceful fish as long as they have enough space.
These fish will be best suited for a tank with filament barbs and leopard danios, neon tetras, ember Tetras, mosquito Rasboras, and ember Tetras.
Scarlet Badis (Dario dario)
| Size | 0.79 Inches (2cm). |
| Lifespan | 4-6 years |
| Care Level | Medium |
| Water Temperature | 75-79 degrees F |
| pH | 6.5-7.6 |
| Behaviour | Semi-Aggressive |
Scarlet badis are my favorite fish. They even surpass bettas. These fish almost look animated with the striking contrast of silver and orange bars.
These fish live in the shallow, clear waters of India’s Brahmaputra river and its sandy gravel substrate. They are also among the smallest percoid species.
These fish, although small, are predators. Their diet must include plenty of meaty food. Many specimens have been known to repel dry flakes or pellets.
You might need to give live food, such as insects, larvae, small worms, or small crustaceans, to your clients.
These fish are shy and peaceful when first introduced to a new environment.
Aggression and territoriality are natural traits that will be revealed sooner or later. They are very intolerant of other fish, even those from the same species.
Scarlet badis tankmates would include pygmy corys and small gouramis, pygmy rasboras and galaxy rasboras.
Endler’s Livebearers, Poecilia wingsei
| Size | 1.5 Inches |
| Lifespan | 2-3 years |
| Care Level | Medium |
| Water Temperature | 75-85 degrees F |
| pH | 7.0-7.5 |
| Behaviour | Peaceful |
Endler’s Livebearers are small fish that can reach 1.5 inches in length. These fish were originally from Venezuela’s heavily planted river basins and would love to have plenty of plants in their tank.
Many people find this fish’s sleeping patterns quite unusual. They drift slowly down to the bottom after falling asleep at the top.
Endler’s livebearers, like guppies are omnivores. They love to eat live/dried/frozen meaty food. You should give them larvae, bloodworms, brine shrimp, bloodworms and insects often.
They also enjoy their greens. You can also give them blanched vegetables like zucchini and cucumber along with high quality flake food.
They are social and peaceful species that can get along with all fish in a tank. You should not pair them with large predatory fish.
These fish are ideal tankmates with honey gouramis, honey tetras and glassfish.
Frequently Asked Questions
Can Tropical Fish Live Without A Filter?
Your tropical fish will live for a long time without filter if the tank is well-planted, has low stocking numbers, clean water, and you maintain it. However, eventually ammonia and even nitrite can build up in the water making it toxic to your fish.
A reliable filter is a must for tropical fish.
How To Keep Fish Alive Without A Filter?
While there are some tricks that you can do, it is not a guarantee that your fish will live a long and happy life.
However, a tank that is well-planted, has regular water changes, tests for bacteria, and provides a good environment for good bacteria can all help to keep fish healthy.
How Long Can A Pleco Live Without A Filter?
The pleco’s health and tank environment will determine how long the fish can survive without a filter.
Your pleco will live for quite some time if the tank environment is well maintained – regular water changes, regular temperature tests, stable temperature and proper aeration.
However, I would still advise against it. It’s impossible to know what is going on in the water.
Can Gouramis Live Without A Filter?
Gouramis can live indefinitely without the use of a filter. The right question is “How long can gouramis survive without a filter?”
Gouramis are extremely tough fish. However, they will still struggle and suffer if the tank isn’t equipped with a filter. Their lives will be affected by toxic ammonia and other nitrates.
How Long Can Neon Tetras Live Without A Filter?
A neon tetra can live without a filter for as long as a few days or weeks. All it comes down to the health of your tetra and the tank’s environmental conditions.
They can live for a few weeks if the neon tetras stay healthy and the tank is clean. Your neon tetras will only survive for a few days if they are in poor health and the tank is dirty.
Final Words: Fish That Don’t Need A Filter
True to form, fish do not require a filter in closed systems like tanks. However, some fish are more tolerant of rookie mistakes and can tolerate filters for longer periods of time.
The fish I have mentioned are some of the most hardy in the hobby. They can survive without a filter for certain periods of time if their tank is healthy and safe.
No fish will survive more than two days if their tank is dirty or polluted.