The Best Fish For a 5 Gallon Aquarium (And Small Tank Benefits)

by Kevin

5 gallon aquarium aquascape.

5 gallon fish tanks make excellent aquariums.

I hear a lot of advice that goes something like, “for the price of a 5 gallon tank you could get a 10 gallon and have more fish.”

And that is often true.

But, sometimes, a 5 gallon tank is the better option for your apartment or home and may look better, aesthetically, than a basic 10-gallon tank.

And, in my experience, a smaller aquarium forces you to make more meaningful choices about design and which fish to keep.

So, if you think a 5 gallon tank is right for you, don’t listen to the naysayers and read on to discover what I consider some of the best fish for a 5 gallon tank.

Also, let me point out that most schooling fish are not “ideal” for a 5 gallon.

The issue is that schooling fish feel more stressed when alone or in a small group.

And in a 5 gallon tank, small schools (typically 4-5 fish) are pretty much the maximum you can have unless you want to risk an ammonia spike.

But, I have still included some schooling fish on this list of best fish for a 5 gallon because, in my experience, they are beautiful and more than happy to live in a 5 gallon if given the proper conditions.

1. Betta Fish (Betta splendens)

Male betta fish with blue body and red fins in a planted tank.

Recommended Temperature: 78–80 degrees Fahrenheit (25-27 degrees Celsius)

Betta fish, both males and females, are truly some of my favorite fish.

They have attitude, they stare at you inquisitively, and they look stunningly beautiful.

They also hate other betta fish, and a lot of other aquarium fish too, so having them in their own 5 gallon is perfect.

Female betta fish should also be a serious consideration for your 5 gallon aquarium.

Female betta fish, especially koi bettas, are just as feisty as male bettas but have shorter fins, which gives them an agile and streamlined look, like a colorful torpedo.

If you want to learn more about the differences between female and male bettas, check out my article on female vs male betta fish.

A betta fish is my top pick for a 5 gallon aquarium because you get personality, looks, and intelligence all in one fish.

If you want to learn more about how you can provide the best care for your betta, check out my article on what betta fish need.

And, if you have a new betta, or are about to get one, check out my post on setting up a new betta fish tank.

2. Guppies (Poecilia reticulata)

One male and two female guppies in a planted tank.

Recommended Temperature: 74-80 degrees Fahrenheit (23-27 degrees Celsius)

A tank of about 4 male guppies will create a flurry of activity during feeding and flashes of color every time you walk by.

Guppies are much more energetic than betta fish and are better for those who want to see fish swimming against the glass with excitement for their next meal.

Male guppies come in a huge range of colors, from bright red tails to panda-like coloring.

While female and male guppies can be kept together without aggression, your 5-gallon tank will quickly become filled with baby guppies (trust me, they make a lot of babies!).

If you want to learn more about the differences between male and female guppies, and which are better to keep, check out my article on male vs female guppies.

3. Cherry Shrimp (Neocaridina davidi)

Cherry shrimp on Java Moss.

Recommended Temperature: 72-80 degrees Fahrenheit (22-27 degrees Celsius)

Cherry shrimp are still underrated in the aquarium hobby.

These freshwater shrimp are colorful and extremely enjoyable to watch as they search for algae and food.

Unlike fish, cherry shrimp do not create a large bioload, meaning they do not produce much waste and so your water quality will not degrade as much when you add new shrimp.

This means that you can have 15-20 cherry shrimp in a 5-gallon tank without worrying about the sudden ammonia spikes that the same number of fish would create.

So, cherry shrimp really are one of the best “fish” for a 5 gallon tank.

Also, cherry shrimp are for beginners; don’t let someone tell you that they are for intermediate aquarists only.

Cherry shrimp thrive under the same parameters and care as betta fish or guppies and are hardier than you may think.

I use tap water for water changes in my cherry shrimp tanks and they do not mind that at all (no RO water necessary for cherry shrimp).

If you want to learn more about aquarium shrimp and how to care for them, check out my guide on aquarium shrimp.

And, if you want to learn how to set up a 5 gallon tank for cherry shrimp, check out my shrimp & guppy tank tutorial.

4. Mollies (Poecilia latipinna, Poecilia sphenops)

Balloon Mollies in a 5-gallon tank.

Recommended Temperature :76-80 degrees Fahrenheit (24-27 degrees Celsius)

Mollies are a classic freshwater aquarium fish and have been in the hobby for a long time.

They are also livebearers like guppies and will produce baby mollies at an alarming rate.

Balloon mollies, red one in particular, are lively and full of personality.

A 5 gallon tank can easily handle a group of about 5 male mollies.

The tank setup you need for mollies the essentially the same as for the other fish in this article.

A heater, sponge filter, and light are the main essentials.

5. Pygmy Corydoras (Corydoras pygmaeus)

Pygmy corydoras or dwarf cory catfish sitting on java moss.

Recommended Temperature: 74-79 degrees Fahrenheit (23-26 degrees Celsius)

Corydoras or cory catfish are small bottom dwelling freshwater catfish.

Cory catfish prefer to be in schools and 5 gallon tanks don’t provide most species of corydoras with enough room.

But, thankfully, a nano species of cory catfish exists.

Corydoras habrosus, Corydoras hastatus, and Corydoras pygmaeus are three species of cory catfish that only reach about an inch in length.

But, they may be hard to find as these nano fish have become increasingly popular.

Keeping 5 of these cory catfish in a 5-gallon tank is doable, but make sure you provide frequent water changes to avoid waste buildup and potentially disastrous ammonia spikes.

A sponge filter is ideal for these small bottom dwellers because sponge filters do not produce strong suction or water currents, but provide some mechanical filtration as well as a place for beneficial bacteria to colonize.

Pygmy cory catfish make excellent inhabitants for planted tanks, they love resting on plants and searching for food around plants roots.

They do great in 5-gallon tanks if you maintain their water quality through frequent water changes, but I recommend getting a bigger tank if you plan to keep other fish in the same tank.

6. Neon Tetras (Paracheirodon innesi)

Neon tetras in a planted tank.

Recommended Temperature: 74-80 degrees Fahrenheit (23-27 degrees Celsius)

Neon tetras look like a science experiment involving jellyfish and minnows.

But, the color and glow of the neon tetra is natural and helps these fish stand out in the muddy waters of their native environment, the Amazon basin of South America.

For a 5 gallon planted tank, consider a school of no more than 5 neon tetras.

Neon tetras are tend to be nervous fish and definitely thrive in bigger tanks, but actually make excellent fish for a 5 gallon if given plants and some décor for hiding.

The bright colors of  neon tetras will contrast especially well with a dark substrate and deep green leaves, like those of Anubias plants.

If you plan on getting more than 5 neon tetras, considering upgrading to a larger tank, like a 20 gallon long. Check out my quick guide on neon tetras for an overview of caring for this species.

7. Harlequin Rasbora (Rasbora heteromorpha)

Harlequin rasboras in a planted tank.

Recommended Temperature: 74-82 degrees Fahrenheit (23-28 degrees Celsius)

Harlequin rasboras have an orange hue and a striking black mark about halfway down their body.

Harlequins make excellent display fish for planted tanks and aquascapes because they add contrast to a tank as well as visual appeal.

But, Harlequin rasboras, like neon tetras, prefer to swim in dense schools.

This makes Harlequins less than ideal for a 5 gallon tank but, with frequent maintenance and water changes, a small school of no more than 4 fish can be kept happily.

If you plan on keeping more than 4 Harlequins, consider upgrading to a 20 gallon long as the water quality in a 5 gallon will degrade relatively quickly.

8. Ember Tetras (Hyphessobrycon amandae)

Ember tetras in a planted tank.

Recommended Temperature: 72-82 degrees Fahrenheit (22-28 degrees Celsius)

Ember Tetras, as their name suggests, are reddish, coppery fish from central Brazil, with populations in the Araguaia River basin as well as other rivers in the area.

Their native habitat is densely packed with vegetation and the water is often discolored and murky from the tannins that leach from decaying leaves and wood.

Ember tetras are ideal for a 5-gallon tank because they are small fish, reaching around .8 inches (2 cm).

Like other small tetras, Ember Tetras do best in schools.

Because space is limited in a 5-gallon aquarium, a school of no more than 4-5 Ember Tetras ideal.

If you want a bigger school of these elegant fish, then I recommend getting a 20 gallon long, which has more horizontal space for these fish to use.

In general, Ember Tetras seem to be less shy than other small tetras like Neon Tetras.

If you plan on setting up a planted 5-gallon tank, and are looking for peaceful fish that are calming to look at, then I highly recommend considering Ember Tetras.

9. Celestial Pearl Danio (Danio margaritatus or Celestichthys margaritatus)

Celestial pearl danio in a planted tank.

Recommended Temperature: 70-79 degrees Fahrenheit (21-26 degrees Celsius)

Celestial Pearl Danios, also known as Galaxy Rasboras (Danios is more correct), are small, peaceful community fish with bright orange accents on their fins and a unique pattern of white spots on their bodies, which, as their name suggests, resemble stars, or galaxies.

These small fish grow up to 1 inch in length, making them ideal for a 5-gallon tank (or a 10-gallon if you want to keep a larger group).

Celestial Pearl Danios do well in heavily planted tanks and make excellent tank mates for a variety of other tropical fish in this article.

Fish Not to Have in a 5 Gallon Tank

1. Goldfish

Goldfish in planted tank.

Goldfish are beautiful creatures but a 5-gallon tank is too small.

Goldfish are big waste producers and water quality can quickly reach a danger zone in a 5 gallon tank.

If you want to keep goldfish, consider keeping them in a small patio pond or get yourself between a 20 gallon and 40 gallon tank.

2. Angelfish

Angelfish in a planted tank.

Angelfish are stunningly beautiful but become far too large for a 5 gallon aquarium.

Angelfish like being near other angelfish but will fight each other without adequate space.

They also tend to be nippy toward other fish.

3. Other Cichlids

Cichlid in a planted tank.

Cichlids, like Oscars, Jack Dempseys, Green Terrors, and countless others, make poor residents for 5-gallon tanks because they grow big and tend to be extremely active.

Also, most cichlids are territorial and need extra room if kept together in a tank.

If you know you want to be a cichlid keeper, definitely skip the 5-gallon tank and go straight to a 20 gallon or larger.


A 5 gallon tank is for someone who likes a challenge.

With limited space, choosing the best fish, plants, and decorations becomes a game of chess.

Putting too many fish in a 5 gallon can quickly lead to a tank crash and the demise of your fish.

But, a thriving 5 gallon aquarium is a work of art.

If you want to learn about aquascaping a small tank, check out my step-by-step guide on creating a 5 gallon cave aquascape.

Larger tanks, like a 20 gallon long are also fun, especially if you want to keep multiple species of fish, but if you crave the challenge of building a vibrant and intricate ecosystem, consider getting a 5 gallon aquarium and filling it with plants.

For more information about plants that can thrive in a 5 gallon tank, check out my article on almost unkillable aquarium plants.

And, check out my article on the best freshwater algae eaters; every fish keeper deals with algae at some point.

If you are interested in keeping slightly larger fish, or a greater number of smaller fish, check out my article on the best fish for a 10 gallon tank.

Or, if you want to learn about setting up an even smaller tank than a 5 gallon, check out my step by step guide to aquascaping a 3 gallon betta bowl.

The reward of small tanks comes from the effort and care we put into them.

As always, stay zen aquarists.