10 Best Fish for 1 Gallon Tank (Complete Guide)

Best 1 Gallon Fish

Every aquarium requires a good amount of water in the tank, because, obviously, most fish require lots of water to thrive. It is thus often recommended to have a tank that can hold a few gallons of water.

Besides, more fish in the aquarium means that you will require more water, and so water capacity is a key consideration when choosing and maintaining your aquarium. However, if you are constrained by the amount of water you can provide, but you still want to keep fish, well don’t despair – all hope is not lost!

Recommend 1 Gallon Fish Tank:

The ideal environment for fish keeping requires you to have ample space for the fish to swim around effortlessly – and really this does mean that you will need much more than a one-gallon tank.

This is why many seasoned aquarists choose a larger fish tank. But of course, so long as you are meticulous about providing the right level of care, then it’s perfectly possible to successfully keep fish in a one-gallon fish tank. In fact, there are a number of fish species that will do just fine in a one-gallon tank.

Some fish species that can be successfully kept in a one-gallon tank include:

  • Guppies
  • Bettas
  • Tetras
  • Paradise Fish
  • Endler’s Livebearers
  • Zebra Danios
  • White Cloud Minnows
  • Dwarf spotted danios
  • Glowlight tetra
  • Goldfish (Not Recommended)

Best Fish for 1 Gallon Tanks

Keeping fish in a one-gallon tank may seem easier to manage than with larger tanks, simply because of the size. However, although it does have its perks, it might actually prove to be even more difficult. Many beginners usually prefer to start small, so as to not go beyond their initial capabilities.

But when keeping a one-gallon tank, you must have a precise way of managing the fish in it. Depending on the fish you choose to have, knowing how to care for them is very important.


Guppies are one species of fish that you can keep in a one-gallon fish tank. Looking at the physical features of guppies, they are very small and even when fully matured, they can live comfortably in a one-gallon tank. Check these Assorted Guppies on Amazon.

guppy fish

It is, however, better to keep only guppy fry in such a small tank, and not the matured fish. Guppies require good water conditions and would not survive in unclean water. Thus, a one-gallon tank would need to have its water frequently replaced. Keeping a small tank clean might actually require more effort than with a larger tank – as it gets contaminated with waste matter very quickly. It is therefore essential to have a water filter.

Being a schooling fish, guppies do not like being alone. You could maybe keep two or three in a small tank, under the strictest care to keep them healthy and happy.

They are a quite friendly species and are not likely to harm one another.


Keeping a betta fish in a one-gallon tank is entirely possible. Although a small tank won’t provide the best conditions, bettas are very hardy and can survive in uncomfortable water conditions. You can Buy this Really Cool Betta fish on Amazon.

Betta Fish Flaring

They also have a labyrinth organ which requires them to frequently come up for air. This allows them to survive in poorly oxygenated water, as they can get some oxygen from the atmosphere.

In a small tank, they would find it easy to come up for air, but in any case you still need to be careful about keeping bettas in such conditions.

You should only ever keen one betta in such a small tank. Having more than one would be very unhealthy and the fish wouldn’t survive

Paradise Fish:

For a one-gallon tank, a paradise fish is a fairly good option. This is because it can survive in several different water conditions, ranging from comfortable to not-so-comfortable.

They are also easy to care for, and are not fussy eaters. Thus, they are often preferred by hobbyists who are new to fish keeping.

It is important to closely monitor the hygiene and health of the fish. You would need to check the fish daily for stress, unhappiness or tiredness.

White Cloud Minnows:

This is another kind of fish that can comfortably survive in a one-gallon tank. This is because they are especially easy to take care of and they remain really small, growing to only about one inch.

As long as they are kept in a planted tank, in a small group of three (to form a school), with a good feeding routine, they will do really well. Many beginners like this fish because they are easy to please and are quite hardy.

They are freshwater fish and do not give any trouble, so long as the tank is kept clean. Many people think that small fish are malnourished. This is not the case for the White Cloud Minnows – they are naturally small and therefore suited to a smaller tank.


Keeping tetras makes you feel like an expert aquarist. But before you get overexcited, please be careful about keeping them in a one-gallon tank. They should be fine in a small tank, but there are many different varieties, each with their own requirements.

Some varieties are relatively small fish (check which kind you’ve got!) and are also very peaceful. They can be kept in a little school of three fish in a one-gallon tank.


Just be aware that there is a variety of different tetras and you need to do your research (and check with the store) to confirm the exact nature and features of that specific fish.

Being a hardy fish, they don’t require any tedious water care besides the regular hygienic care needed for a small fish tank.

Glowlight Tetras:

Having a single glowlight tetra in a one-gallon fish tank is possible. It is not especially difficult to care for, but may do better in a small school of three.

They are quite peaceful and friendly, and make good community fish. Being small in size also makes them a good option.

Their bright appearance adds color to your small tank, and makes them quite fun to keep. You should however be careful about any tank mates they might have.

Their fins might get nipped at by other active fish that find them interesting. In essence, you can keep this kind of fish in a one-gallon tank, but only temporarily if they are to have a long, healthy life.

Endler’s Livebearers:

This species of fish is quite similar to guppies and is a really good option for a small tank as they are very small in size (about one inch).

Endler’s Livebearer

They are peaceful, and come in a variety of colors but cannot be kept in large numbers in a small tank.

Just a small school is required and also a good amount of floating aquatic plants to keep them covered from light. This fish isn’t too demanding when it comes to the right water parameters, and requires a reasonably warm water temperature.

Zebra Danios:

This is another good freshwater aquarium fish suitable for a one-gallon tank, due to their small size. They are a lovely, beautiful fish to keep, having a zebra-like striped body.

Being active and hardy fish, they can survive an incredible range of water conditions and do not fuss over one special diet. You don’t even need to use a water heater in the tank. You should however take note that they are active breeders, and being made to breed in such a small tank might not be such a good idea.

This means you should not keep matured zebra danios of the opposite sex together.

You should also make sure that you do not have a giant danio instead of a zebra danio. Also, you shouldn’t keep them with aggressive fish, as this might stress them further and shorten their lifespan.

Dwarf Spotted Danios:

The dwarf spotted danio is known to be even smaller than the zebra danio and is hence suitable for a one-gallon tank. They are easy to keep, and are quite hardy to most water conditions.

You need to monitor the fish over the first few days in a small tank as it might get tired after swimming in a small place for a long time.

This fish looks really nice, but you must be careful to ensure that the water doesn’t get contaminated with toxic matter or waste deposits. Cleaning the water often, as well as having a water filter is essential.


Almost everyone has come across a goldfish being kept in a small bowl at home or in an office. While this might actually look pretty, this is definitely not a good for your fish.

Goldfish Aquarium

Although keeping your goldfish in a one-gallon tank is a better option than a bowl, as it provides more space, the fish would still require careful attention. Of course, you cannot keep more than one goldfish in a tank this small.

And as goldfish get really messy and produce even more toxic matter than the average aquarium fish, it would take extra care to ensure that the water tank is kept in a hygienic condition.

You would also have to be careful about the goldfish’s diet. In such a small tank, you wouldn’t want to overfeed your fish. Firstly, this would weigh it down, but also it would result in more waste accumulating in the tank and further increase the level of contamination.

Many seasoned aquarists would advise against keeping a goldfish in a one-gallon tank, but it’s fine as a temporary measure for a small goldfish. But you will have to move to a bigger tank eventually! 

Hobbyist or not, you must ensure the best living condition for any creature, whether in a one-gallon tank or a larger tank.

How many fish should you keep in a one-gallon fish tank?

The fact remains that a one-gallon fish tank is very small. Thus, you shouldn’t really have more than one fish in it. It is okay for a hobbyist who is just starting out as it’s easy to manage and care for. A single betta would do fine by itself in a tank that small.

For schooling fish, you could temporarily keep two or three small fry in a tank this size, so long as they would be moved to a more suitable environment before they grow too large.

Also, avoid keeping fish of opposite sexes, so as to prevent breeding in such an environment. Keeping an aggressive fish in such conditions would also trigger more aggression, and neither should you put two territorial male fish in a one-gallon tank. They would get very hostile and one is likely to kill the other. Hence, a one-gallon fish tank is only really suitable when there is only one fish housed in it.

How many tetras should be kept in a one-gallon tank?

Ideally, no more than one fish should be kept in a one-gallon tank. But a schooling fish requires at least two or three to keep them happy. As said, it would, however, require more devoted care to keep multiple tetras in such a small fish tank.

How many goldfish should be kept in a one-gallon tank?

If you must keep a goldfish in a one-gallon tank at all, you must be extra-meticulous. You should certainly never have more than one goldfish in a tank this size. As said above, they are also really messy and will quickly pollute the water.

Keeping more than one goldfish in a one-gallon tank would be a death sentence. To ensure the welfare of your goldfish, use a water filter and be religiously committed to frequent and proper water changes.

How to maintain a one-gallon fish tank

While it is true that your fish requires much more space than that offered by a one-gallon fish tank, it is possible to keep your fish healthy in it if you know the right things to do.

First you must be extremely particular about the hygiene. Because of the small amount of water, waste deposits build up more quickly, and messy fish like goldfish would require cleaning about 2 times a week.

Changing 30-50% of the water every few days, or constantly checking ammonia levels is a good way to ensure balance and hygiene. In fact, your one-gallon fish tank really needs to have a small filter to keep the tank hygienic.

Most people who find that they cannot cope with this frequency of maintenance opt for bigger tanks.

Also, you would have to reduce the level and amount of feeding given to a fish in a one-gallon tank. It is well known that the more food you give your fish, the more waste is produced. Excess food also produces even more waste deposits in the fish tank.

Reducing the feeding to just once every two days, and in smaller proportions, helps to keep the fish tank cleaner and healthier. This is especially good for fish species that are naturally small and grow no more than 1-1.5 inches upon maturity.

Temperature and lighting

In addition, you must ensure that the temperature, lighting, and pH scale of the water is always balanced. This would reduce the exertion on your fish and would help it conserve energy.

Fish like bettas are quite peaceful and would only get agitated if the conditions of the water are drastically changed. They prefer the water to be kept on the warm side.

Thus, keeping a betta in a one-gallon tank would require you to keep the water at a steady, warm temperature (and definitely not outdoors). 

Aquatic plants will also help to oxygenate the water and create conditions similar to the fish’s natural home environment.

In other words, when you replace the water, you need to check its temperature and condition before introducing it to the tank.

The water you’re using must be as close as possible to your tank temperature, either by using a heater or by letting the water get adjusted to the same room temperature.

Also, do not forget that the substrates, plants or any decorations need to be cleaned as well, as a lot of waste gets stored amidst them.

Finally, your fishkeeping should not be at the detriment of your fish’s health. Thus while this article explains the possibility of keeping different kinds of fish species successfully in a one-gallon tank, you should strive to get your fish in the best living conditions, in bigger tanks and always maintain excellent levels of care.

Saurabh Kumar

I am a passionate fish keeper, with years of experience. You will find some really useful tips and information on this blog about Freshwater Aquariums.

3 thoughts on “10 Best Fish for 1 Gallon Tank (Complete Guide)

  1. a one-gallon tank is too small for any fish betta fish needs at least a 2.5-gallon tank and goldfish need at least a 20 gallon for one. you couldn’t even keep shrimp in a 1-gallon tank.

    1. I completely agree with you! But this is just a helpful post for those who have limited space and want to explore the hobby, and in most cases, a 1-gallon tank is a temporary solution!

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