How To Stock A 5 Gallon Fish Tank

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If you’re looking for a compact aquarium to keep in tight quarters or you just want a cute, little tank to fill with tiny fish, then getting a 5-gallon aquarium is the best option.

They are one of the most popular tank sizes, but also ones you need to clean most often.

5 gallon fish tank combinations
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Let’s look at what type of fish thrive best in a 5-gallon fish tank as well as how many fish fit in a 5-gallon tank, and how to best set it up.

What Are the Best Fish for a 5-Gallon Tank?

Typically, the best fish for a 5-gallon tank include:

  • Betta fish.
  • Killifish (or Heterandria Formosa).
  • Any dwarf shrimp species.
  • Thai micro crabs.
  • Nerite or assassin snails.

You can even fit some of these species in the same tank, due to their relatively small bio-load.

There are many great 5-gallon tank fish combinations out there, but shrimp and snails often match best with any companion other than bettas.

Bettas can be territorial and may eat other species that occupy the tank. If they do become aggressive, it’s best to transfer these species to their own tanks or bowls.

Other fish species may be deemed suitable for a 5-gallon aquarium, but they will actually thrive better in a much larger tank.

Varying activity levels, speed of growth, and an inability to handle unstable water qualities are all factors that play into whether or not a species will do well in a small tank.

Unfortunately, these species weaken due to a lack of space:

  • Fancy goldfish.
  • Common goldfish.
  • White cloud mountain minnow.
  • Celestial pearl danio.
  • Dwarf pufferfish.
  • Neon tetra.
  • Guppies.
  • Endler’s guppies.
  • Apple and mystery snails.
  • The Rasbora species.
  • (Pygmy) Corydoras.

how many fish in a 5 gallon tank

How Many Fish Can Be in a 5-Gallon Tank?


You should only keep one betta in a 5-gallon aquarium, as they will fight others of their species to the death if kept confined.

If you want to keep killifish, on the other hand, limit your tank to only two at the most.


Shrimp are one of the top fish people like to keep in these smaller aquariums, due to how small they are themselves.

However, some species, such as the red cherry shrimp, will also breed frequently, so keep this in mind before buying too many at the start. You may fit up to 10 dwarf shrimp species in a tank of this size without much of a problem.

The best shrimp species for this include the red cherry shrimp, ghost shrimp, and red crystal shrimp. Orange sakura, yellow shrimp, and blue fairy shrimp may thrive as well, just in smaller colonies of up to about two shrimp per tank.


Mexican dwarf crayfish will also do well in a tank of this size, but you should only keep one crayfish per aquarium.

Though you may want to add more than a single dwarf crayfish to the tank, just know that they become virtually defenceless when they molt. This leaves them open to other crayfish that might want to eat them.


Thai micro crabs will be content in a 5-gallon aquarium but never keep more than five in a single tank.


You can keep up to five snails in a tank of this size, too.

Snail species such as the ramshorn snail, Nerite snails, greater pond snails, Japanese trapdoor snails, Malaysian trumpet snails, or assassin snails will live happily in your 5-gallon fish tank.


If you really want to keep Endler’s livebearers, just be sure your tank consists of only male guppies. If you keep a co-ed tank, chances are the fish tank will become quickly overrun with fry (or baby fish).

A small handful of male Endler’s livebearers will do fine in a standard 5-gallon aquarium. Just know that they may act aggressively towards one another every now and then.

Introducing live plants into the tank will provide them with their own areas, which, in turn, will break their lines of sight and reduce the chances of a conflict.

5 gallon fish bowl

Best Plants for a 5-Gallon Tank

Live plants are a huge benefit to fish tanks, due to their oxygen production and the ability to absorb the ammonia your fish create.

In addition to keeping your water levels relatively even, aquascaping will also make your tank look more vibrant and provide your fish with food to eat in between meal times.

You can decorate your tank with a variety of plants, including:

  • Anubais Nana.
  • Java Fern.
  • Java Moss.
  • Staurogyne Repens.
  • Dwarf Hairgrass.
  • Ambulia.
  • Bacopa.
  • Elodea/Anacharis.
  • Water Sprite.
  • Water Wisteria.
  • Brazilian Pennywort.

Heavy rooters like these will also do fairly well:

  • Amazon Sword.
  • Banana Lily.
  • Tiger Lotus.

How to Set Up a 5-Gallon Fish Tank

You need to keep this tank in a level area away from any windows or sources of heat. You don’t want to accidentally fry your fish!

Most tanks are around 16 x 8 x 10 inches, so figure out what space in your home will best suit your 5-gallon fish tank.

Add Gravel or Sand

Before you put in any water, you should sprinkle gravel or sand along the bottom.

Filters and Heaters

Hook up all your electrical equipment you need, including your tank’s filter and heater if you plan on buying tropical fish.

Investing in a filter is especially crucial to your small aquarium! The more compact the tank, the faster the toxins within it can build up. A good filter will remove these lethal toxins and clear any detritus from the water as well.

Try to purchase a good chemical, mechanical, and biological filter that’s not too powerful. Filters that are too powerful can create a strong current within the small tank, which may stress out your fish.

If you want to raise any tropical fish, keep your heater to around 75 to 80 degrees Fahrenheit.

5 gallon fish tank
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Next, you will want to set up your aquarium’s lights. These lights should promote your live plant’s growth and help regulate a strict circadian rhythm for your fish.

They also enhance the colors of all your fish and plants for your viewing pleasure.

The strength and wattage of the lights you install in your tank will depend on the fish and plants you choose to keep.

Some plants prefer dimmer lighting, while others thrive with brighter lights. Likewise, certain species of fish require bright lighting, while others depend on a natural day-night cycle.

Be sure to research your fish and plant species beforehand, so you don’t set your lights to the wrong brightness levels.

Add Water

To start off, fill your tank up with water and add a water conditioner.

Do not just dump your fish right into the tank! This can send them into shock and they may die.

Instead, introduce them to the water in the tank slowly, so they can grow accustomed to the new environment.


Last but not least, you will need to add decorations to your aquarium.

Keep in mind the nature of your fish before placing any random decorations inside. Different fish will prefer different types of decorations, all for different purposes.

Hiding Places

More timid fish species will need plenty of hiding places in order to feel comfortable, so be sure you use decorations with holes in them.

Vases, rocks, and logs make for good hiding places.


More active fish species, on the other hand, need a lot of room to swim. As such, use small decorations and plants that they can easily swim around.

best fish for 5 gallon tank

In fact, a good rule of thumb is to just choose smaller decorations from the start. Most aquarium decorations are made with larger size tanks in mind, so you will need to ensure they will actually fit in your tank right away.

Natural Decorations

You should also consider using natural decorations instead of factory-made ones. After all, it is much easier (and way cheaper) to use a cool piece of driftwood or a couple of neat-looking rocks you found than some pre-made decorations.

Natural pieces also have their own unique shapes, which can make your aquarium stand out. Just make sure you thoroughly rinse any natural decorations you pick up before placing them into your aquarium. Even store-bought natural items can contain harmful bacteria that may kill your fish.

Don’t use soap or tap water to clean these decorations! Instead, rinse them off using some of your aquarium’s water and then put them in their own separate tank for a few weeks.

This will allow your natural decorations to build up good bacteria that will be safe for your fish. Once this is done, add the piece to your tank.

Regardless of the species of fish you decide to keep, try to include a few decorations you think they might like to keep them happy and safe.

This video shows an example of how to set-up a 5-gallon tank.

A Note on Cycling Water

Due to your tank’s size, it will require more care and maintenance than larger tanks do. As stated above, smaller bodies of water are quick to accumulate ammonia and other toxins that can be harmful to your fish.

Just know that, if you do want to keep a small tank, be prepared to perform weekly water changes and monitor the tank’s water parameters carefully.

Most people, especially beginner aquarium enthusiasts, may forget to cycle their tanks when they first set them up. Basically, cycling allows the tank to build up good bacteria that helps convert harmful ammonia and nitrites into relatively harmless nitrates, which can then be removed during water changes.

The best part of this cycling process? You don’t need to initiate it!

This nitrogen cycle is a natural process that will occur all on its own. Once the ammonia and nitrite levels have dropped back down to zero after you change your water, your tank will be ready to house your fish and various aquarium plants again.

Fish Tank vs. Fish Bowl

Most aquarium enthusiasts prefer aquariums to 5-gallon fish bowls, due to the many advantages aquariums have over bowls.

Oxygen Levels

For one, the bowl shape minimizes the surface-to-air ratio, which is how much of the water’s surface is exposed to air.

Even though fish are water-breathing creatures, they still require oxygen in their water to survive. The higher the surface-to-air ratio, the more oxygen in your water! This, in turn, allows your fish to breathe.

Aquariums have far larger surface-to-air ratios than mere bowls.

Space for Equipment

Keeping tropical fish also becomes impossible, because of how difficult it is to fit a heater or filter inside of the bowl shape.

This may even make your fish suicidal, and the open-top certainly doesn’t help there.

5 gallon fish tank

Top Cover

Your fish can easily jump out of an open bowl and suffocate on your living room floor while you’re away. The open top also makes it easy for toxins to fall into the water and poison them.

This may be easily solved by placing something over the top, but rectangular aquariums already have secure tops. As such, it’s best to just buy an aquarium from the start.

Closing the top may also prevent oxygen from properly getting into the bowl, which may make it difficult for your fish to breathe.

Size Differences

Bowls tend to be smaller than tanks, even if they supposedly hold the same amount of water.

Limited swimming space can stress your fish out, as well as decrease the oxygen intake that the bowl will give your fish.

The smaller size also means you will have to change the bowl’s water daily, rather than weekly.


A bowl’s curved glass can distort your fish’s view of the outside world, which may stress them out even more.

Placing them in a rectangular or square aquarium will give them as clear a view of you as you have of them, which may help them to recognize you, rather than fear you.

Here’s a video with more information on fish tanks vs. fish bowls.


Despite their compact size, maintaining a 5-gallon fish tank is a great deal of work.

Still, if you clean it every week and incorporate the right number of fish and decorations, this little tank can be one of the most interesting and vibrant projects you can own!

What’s your favorite thing about 5-gallon fish tanks?

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