What Are the Best Fish For a 2.5 Gallon Tank (12 Best Fish)

Estimated read time 12 min read

In this article, we will go over a few of the best fish for a 2.5 gallon tank.

Lastly, we’ll share a few stocking ideas and combos that are sure to impress everyone you work with.


Best Fish for a 2.5 Gallon Tank 

1. Betta Fish (Need a Heater)

Some of the most recognizable aquarium fish, bettas, are known for their brilliant tail fins that resemble a bird’s plumage. They are originally from Southeast Asia and also known as Siamese fighting fish due to their tendency to be territorial and challenge – or even eat – other fish. Bettas, especially males, should be kept in a tank alone. 

2. Endler Guppies (Best Fish For A Small Bowl)

These colorful flashes of activity will dart across your tank and catch the light with their array of attractive coloring. Endlers do much better than bettas at living in schools. 

3. Sparkling Gourami

Gouramis are hardy, low-maintenance, and compatible with a wide variety of other fish and aquarium creatures. They are similar to guppies in appearance. Native to ponds and streams, gouramis enjoy ample vegetation in their habitat. 

4. Ember Tetras 

These slim little swimmers are sometimes called fire tetras for their predominantly red and orange coloring. They also do well in groups with different fish varieties. 

5. Zebra Danios

Thin-bodied and quick, danios are striking in their black-and-white markings that resemble zebras. They are peaceful, quiet, and happiest when placed in community tanks with others of their type. 

6. White Cloud Minnows (Easiest Fish To Care For In a Bowl)

Minnows are native to the brackish water found in streams, not always in warm habitats. For this reason, they have a lower water temperature tolerance point and do well in fishbowls with no heater. In addition, white cloud minnows love to be grouped together. 

7. Pygmy Corydoras 

Cute and tiny, corydoras are excellent for a relatively small tank. They are easy to recognize for their irregularly-shaped bodies but often confused for danios. 

8. Pea Pufferfish

This unique tank species is also called the pygmy puffer and dwarf puffer. Full-grown at only less than one inch long, they are the smallest type of pufferfish in the world. 

9. Six-ray Corydoras 

Like their cousins, the pygmy corydoras, the six-ray corydoras are a diminutive member of the catfish family. Their spotted coloring adds a splash of visual interest to your freshwater school as they hover near the bottom sifting through sand for tidbits.

10. Scarlet Badis 

This variety is rarer than most of the others listed. However, Badis’ dazzling color makes them a lovely addition to a tank with other striking fish such as danios and tetras. Known as a micro predator, badis feed on tiny aquatic creatures such as crustaceans and insect larvae that multiply inside a tank. 

11. Snails 

Diversify the species in your aquarium with these chill little pets. Snails feed on algae and other tank buildup, contributing to a healthy biological balance within their habitat. They peacefully coexist with fish and most other freshwater life. 

12. Shrimp

Quirky and interesting, shrimp love to perch atop plants and other aquarium decor as they skim the surface for tasty snacks. They do well in a shrimp-only tank and cohabitate nicely with peaceful fish (such as guppies and tetras). 

Types of Fish That Should Not Be Kept In A 2.5 Gallon Tank


These grow to the size of their tank and prefer large areas to swim. They also require more in terms of heating and air-pump amenities. 


These are larger fish species and do best in 10 gallons or more. 


Related to piranhas, cichlids grow very large and are aggressive. Therefore, they need at least a 20 gallon tank, though some do best with even more space. 

What Kind Of Fish Can You Keep In A 2.5 Gallon Tank? 

We would all love to have the space, money, and cleaning resources for a magnificent aquarium display. But the reality is that the elaborate 50-gallon setups you see in the dentist’s office are pricey and require significant upkeep. 

For most people, a smaller fish tank has to do the trick. However, beware that when planning for an aquarium of fewer than 10 gallons, there are special considerations for fish size, algae growth, and other limitations. 

So, what can you do with 2.5 gallons? 

Small Fish

The bigger the fish, the more expansive area of water it needs to swim. So it stands to reason that with only 2.5 gallons, you’ll be better off choosing fish that are smaller in size, like guppy or minnow species. 

Some tiny fish, such as tetras, prefer to live in schools of their own type. Just because your aquarium is on the small side doesn’t mean you need to limit yourself to one fish – but do ensure you do your research to decide which variety works best for building a school. 

Hardy Fish

With larger tanks, there are better solutions for maintaining the individual preferences of your fish. In addition, temperature, water quality, filtration, and other amenities are easier to include when you have the space and proper setup. 

But with smaller tanks, there’s not always room for all the extras. Fish sensitive to specific water pHs or excessive algae growth won’t do well in an environment where these are harder to control. 

Choose fish species that are hardy, such as danios or guppies, to extend the life of your fish tank habitat. The ecology will sustain better when the fish are balanced. In addition, types of fish less stressed by temperature fluctuations will do better in a small tank of this size. 

Cold Water Fish

If you have space restrictions on your tank, chances are you won’t be as prone to setting up a heater for it. Fish who are native to mid-range climates, such as minnow varieties, will be perfectly content to swim around in water that matches the temperature of your home’s air. 

A temperature range of 50-75 degrees Fahrenheit will be sufficient for most of the varieties listed above, except bettas, which require a heater. 

How Many Fish Should You Keep In A 2.5 Gallon Tank?

The rule of thumb for freshwater aquarium fish is one gallon of water per one inch of fish. So in a 2.5 gallon tank, you could group together, for example: 

  • Two or three one-inch-long fish
  • Multiple tiny fish of the same type
  • One larger fish alone, like a betta

Think also about the vertical strata that the fish like to occupy. If you have guppies and tetras flitting close to the water’s surface, you can get away with adding a different kind of aquatic creature that prefers to hang out towards the bottom of the tank. This might be a shrimp, snail, or catfish-related species listed above, like corydoras. 

Keeping Fish In A 2.5 Gallon Tank – What You Need To Know 

Ok, you’ve got your tank set up and have decided on the fish you want to stock it with. What else do you need to do to ensure the health and safety of your new pets? 


A 2.5-gallon tank doesn’t necessarily need a heater, filter, or other accessories – though they help maintain better ecological quality for your fish. At the bare minimum, your tank should have: 

  • Lighting with day and night settings to provide a natural schedule for the fish to rest 
  • Rocks, sand, or some gravel to line the bottom (called the substrate)
  • Aquarium plants or decorative structures
  • An accompanying net to scoop out impurities from the water 
  • Water conditioner
  • Aquarium test strips to check the water quality 

Your local pet store sells all of these items and may have additional ideas for you as you imagine what sorts of fun or beautiful decor you want your tank to feature, such as themed stones and faux plants. 

How Often To Change the Water 

Switch out 25% of the water every few weeks for optimal health and happiness for your fish. They can remain in the tank while you do this, or you may choose to remove them to a safer location while you work. 

The more fish you stock your tank with, the more waste they will produce, and the more often you need to change the water. On the other hand, if you choose creatures who like to nibble on algae buildup (such as a plecostomus), they will naturally take care of some of this. 

Never change out more than half the water at once, as this rids the aquarium of organic bacterial growth. 

Beautiful 2.5 Gallon Tank Ideas And Stocking Options


With a tank on the small end, your decorative options are somewhat limited, but there are enough choices to fit the tank aesthetic you like. 

Consider a theme, like ancient Greece with tiny, open architectural structures the fish can zip through back and forth. Or maybe you’d prefer color coordination with hues that match or complement the markings of your fish. Perhaps you’d like to reflect a particular geographic region, such as Japan, with small pagodas for shrimp to perch on. 

Your tank could be futuristic or more natural, glamorous or understated, with jewel, pastel, or earth tones. The options are virtually endless. 


As a fish tank is a beautiful combination of pet and visual display, you should choose animals and decorations that look attractive together.

For a 2.5-gallon tank, you could choose one large fish like a betta or multiple smaller fish swimming in schools. There are also companion animals, such as crustaceans, who enjoy the camaraderie of fish in their habitat. 

Make sure to prepare your setup and then let the water sit for at least 24 hours before stocking the tank with fish. This allows the water levels to settle and any chlorine or other harmful chemicals to evaporate. 

Once the aquarium is ready, go ahead and add the fish. Set the bag containing your pet into the water and let it float for half an hour to allow the water temperatures to stabilize. Then, dump the fish along with its water from the store into the tank. It will take some time for them to adjust to their new environment, so don’t be alarmed if your fish seem to be lethargic at first.

What Aquarium Plants Can You Add To A 2.5 Gallon Tank?

Another choice you need to make when setting up your tank is using natural or artificial plants. Including one or the other is crucial for fish—especially the smaller species—as they use the plants to hide and lower their stress levels. 

Your local pet supply shop has rows of faux plants to set into your aquarium. They are non-toxic and run in every color and shape imaginable. 

However, you might be more interested in living plants contributing to your tank’s ecosystem. Some live plants that work well in a 2.5-gallon tank are: 

  • Sagittaria
  • Rotala Rotundifolia
  • Green Hygrophila
  • Java Fern
  • Anubias
  • Green Hygrophila
  • Sunset Hygro
  • Waterwheel Plant
  • Moneywort
  • Rotala Indica
  • Java Moss
  • Hornwort
  • Vallisneria

Our Recommendation For The Best Fish To Keep In A 2.5 Gallon Tank?

Perhaps, the easiest fish to take care of in 2.5 gallon fish tank is White Cloud Minnows. It’s small (grows up to a maximum of 1.5 inches) and hardier than most small schooling fish, and can withstand most of the mistakes by novice fish caretakers. The only exception is copper medication.

Our Recommendation For A Great 2.5 Gallon Fish Tank


How many fish can I have in a 2.5 gallon tank?

You can keep 3-5 small fish, one larger fish like a betta or gourami, or a few crustaceans in a 2.5-gallon tank. 

How many neon tetras can I put in a 2.5 gallon tank?

You can keep 3-5 guppies in a 2.5-gallon tank. These are friendly fish who enjoy the company of their species. 

How many guppies can you have in a 2.5 gallon tank?

You can keep 1 to 2 guppies in a 2.5-gallon tank.

How many goldfish can I put in a 2.5-gallon tank? 

Goldfish grow to size in their surrounding environment and need lots of space to swim. Therefore, it’s not a good idea to put goldfish in a 2.5-gallon tank. 

Can I keep a betta fish in a 2.5 gallon tank?

Yes, but just one, as they take up more space than some of the smaller varieties of fish. Females do better together than males, so you could feasibly group 2 betta females in a tank this size, but larger would be better. 

Before you go check out our list of the best freshwater aquarium fish you can use in your next tank.

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