2.5-gallon fish tank: Our top six picks for you

Alison Page

Alison Page


2.5 Gallon Fish Tank

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Did you know that, according to the National Pet Owners Survey 2019-2020, after cats and dogs, fish are the most popular pet in U.S. households? Watching a sparkling collection of fish swimming around a beautiful, aquascaped aquarium is also proven to reduce stress, lower your blood pressure, and even calm kids with ADHD.

Well, the good news is that you don’t need a huge aquarium to enjoy the benefits of keeping fish. A small fish tank is just as enjoyable and takes less time to maintain, so it’s a win-win!

In this article, we take a look at six of the best 2.5-gallon fish tanks that are on the market today. Also, we explain in more detail what’s so great about having a home aquarium, and we take a look at what fish species you can keep in a small 2.5-gallon fish tank.

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Best 2.5-gallon Fish Tanks

So, here are our favorite 2.5-gallon aquariums that you’ll find on the market today. To find out more and order one of these aquariums, simply click on the in-text link provided.

Koller Products 2.5 Gallon Aquarium

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Measuring just 9.5″ x 9.5″ x 11.2″, the Koller Products 2.5-Gallon Aquarium is the perfect size for a small apartment or to display in your bedroom.

This aquarium kit comes with a bright LED lighting system that features a choice of seven colors, including aqua, blue, green, purple, amber, white, and that you can vary to match your room’s d├ęcor system or your mood. There’s also an incorporated timer that enables you to select the color you want and decide for how long you want that color to display.

Crucially, and unlike many small fish tanks, the Koller has an internal filtration system that keeps the tank water clean and free from ammonia and nitrates. The tank is made from impact-resistant plastic, and it’s constructed in one piece, removing the risk of leaky seals.

What we like:

  • High customer ratings
  • Comes complete with all accessories required and a clearly-written instruction manual
  • LED colored lighting unit with timer
  • One-piece construction removes the risk of leaks
  • Perfect size for small spaces
  • Has a powerful yet quiet-running filtration system

Room for improvement:

  • Too small for many species

Fluval Spec III 2.6 Gallon Aquarium

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The Fluval Spec III is a neat, nicely presented table-top aquarium that measures just 11.8″ x 10.8″ x 8.7″. The design is very modern, and the kit comes with all the accessories that you need.

There’s a very powerful, three-stage filtration system with a fully adjustable output nozzle that keeps the tank spotlessly clean and healthy for your fish. The aquarium is made from glass that’s treated to be crack-proof and scratch-resistant. The aquarium kit features LED lights, and you can upgrade the color of the lighting if you wish.

The filter system is extra-powerful and cleverly concealed so that all you see is your fish and plants.

What we like:

  • Super-powerful filtration system for ultra-clean water
  • Easy to set up and maintain
  • Ideal for beginners
  • Quiet enough for a bedroom or workstation

Room for improvement:

All-Glass Aquarium AAG10002 2.5 Gallons

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The All-Glass Aquarium by Aqueon is precision-built from strong, scratch-resistant glass and comes with classic black or oak trim. The tank measures 12.2″ x 6.1″ x 8.1″, making it suitable for table-top use.

This is not a complete aquarium kit, and you do need to buy a filtration system, lighting system, and heating unit. The tank is well-made and would make a good choice for you if you want to build your aquarium entirely from scratch.

What we like:

  • Well-made product
  • Perfect for those who want to start from scratch
  • Ideal size for small homes

Room for improvement:

  • Doesn’t come as a complete aquarium kit

Tetra GloFish 3 Gallon Aquarium

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The Tetra GloFish 3 Gallon fish tank is the ideal tank for a small space, measuring just 10″ x 10″ x 10.5″.

This cube-shaped tank is made from toughened plastic that’s shatterproof and crack-proof, making the aquarium an ideal choice for a child’s bedroom or even a school classroom environment.

The tank comes with a powerful three-stage filtration unit to keep the water clean, and it has an LED light source over the top of the tank to highlight the fish swimming beneath. Unfortunately, the unit does not come with a heater included, so you’ll need to buy one separately if you want to keep tropical fish.

What we like:

  • The compact size makes the tank ideal for desktops or classrooms
  • Shatterproof acrylic product for safety
  • Includes a powerful filtration system
  • LED light unit
  • Stylish design

Room for improvement:

  • Does not include a heater, which you’ll need for tropical fish
  • Some users complained that their fish and dwarf frogs were sucked into the filtration unit and injured

Koller Products AquaView 360 3 Gallon Aquarium

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This aquarium from the reputable manufacturer, Koller Products, gives a remarkable 360-degree view of the tank and its occupants, making it ideal for display on a coffee table or in a child’s bedroom. The tank measures 10.2″ in diameter and is 14.5″ in height.

The Koller Products Aquaview is a column-shaped tank has super-bright LED lights that give you a choice of seven colors to reflect your mood, including daylight white, green, blue, purple, red, aqua, and amber. There’s a built-in timer too so that you can set the lighting to come on at certain times.

Like most Koller aquariums, this one includes a high-quality filtration system with a high flow rate of 25 gallons per hour, which will keep the tank water fresh and free from ammonia and other nasties that could harm your fish.

The tank is constructed from impact-resistant plastic for a super-clear view of your fish, and the seamless design removes any concerns about leaks. You’ll need to provide three AAA batteries to run the filtration system, and the unit includes a 5V power adapter so that you can connect the lighting system to the mains.

Unlike many similar products, the Koller Aquaview 360 comes with a 100% customer satisfaction guarantee.

What we like:

  • Stylish, trendy design
  • Tank includes a powerful filtration system and LED lighting
  • Leak-free design
  • 100% customer satisfaction guarantee

Room for improvement:

  • Some users noted that the filter unit was noisy and underpowered
  • The tank doesn’t include a heater

MarineLand Contour Glass Aquarium Kit

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The MarineLand Contour Aquarium Kit is a sophisticated, elegant, curved glass tank that adds a touch of class and style to any room. The unit measures 9.5″ x 9.5″ x 10″.

The aquarium has a rail light system that’s equipped with bright blue and white LEDs and can be set to a daylight or moonlight lighting effect. The tank has an advanced three-stage filtration system, including an adjustable flow rate, mechanical, and chemical filter media. The tank design hides the filtration system so that it doesn’t spoil the look of your display.

The tank has a glass cover slide that provides easy access to the filter for cleaning and makes feeding your fish easy and hassle-free.

What we like:

  • Smart, stylish design
  • Bright LED mood lighting system
  • Comes with an advanced three-stage filtration system

Room for improvement:

  • Doesn’t include a heater
  • Filter pump is quite noisy

Benefits of a home aquarium

There are many benefits to keeping a home aquarium!

Not only does a beautifully decorated setup that’s full of lively fish look great, but a fish tank an also improve your mental and physical wellbeing.

Reduces blood pressure

According to research, a home aquarium can help to lower your blood pressure. And a tank that has living fish results in a larger drop in blood pressure than a tank that contains nothing at all or fake fish!

Not only that, but a tank that contains a variety of fish species is even more effective at reducing heart rates and blood pressure.

Reduces feelings of anxiety and fear

Does your dental office or medical center have a fish tank in the reception area?

Many do, and that’s because those patients waiting in a clinic with an aquarium to look at were much more chilled out about their visit and even needed reduced pain medication when compared to those in clinics that did not have a fish tank. Also, a study shows that watching the activity in a fish tank is more relaxing than meditation and hypnosis. Who knew?

Calms kids with ADHD

Does your child suffer from Attention Deficit Hyperactivity Disorder (ADHD)?

Well, research has shown that ADHD and autism sufferers become calmer when there is an aquarium in their home. And if you don’t want the hassle of caring for fish, a DVD or screensaver featuring fish swimming in a blue ocean or gliding among plants in a tropical lagoon can be just as effective as the real thing.

Helps Alzheimer’s patients

In the United States, there are over five million people living with dementia or Alzheimer’s Disease. And, according to the U.S. Alzheimer’ Association, that number could be as high as 16 million by 2050.

So, it’s great news that a fish tank full of shimmering shoals of tropical fish can help to change the behaviors of Alzheimer’s patients. A study showed that disruptive behaviors were reduced, and some patients’ appetites even improved, simply through being exposed to a fish tank.

Reduces anxiety and stress

The presence of a home aquarium can help to reduce the levels of stress and anxiety in many people, resulting in an improvement in mental health and promoting general feelings of wellbeing. That’s according to 67% of those fishkeepers surveyed by the American Pet Products Association.

10 Best fish species for a 2.5-gallon fish tank

Before you splash out on a 2.5-gallon fish tank, you’ll need to know what kind of fish you can keep in it. This is a small tank, and it’s unsuitable for large species. Remember that a tiny fantail goldfish can grow up to 8 inches in length and may live for 20 years or more, so you can see that a 2.5-gallon aquarium won’t be suitable.

How many fish?

When it comes to stocking a fish tank, the general rule of thumb is to allow 1 gallon of water per 1 inch of fish. So If you have a tank of 3-gallons’ capacity could accommodate a few tiny tetras or one betta fish.

Overstocking a fish tank will place a strain on the filtration system, leading to poor water quality and stressed fish that may become sick. Also, many species of otherwise peaceful fish will become aggressive if the habitat is overcrowded.

So, when choosing fish for a small tank, always think quality, not quantity.

Betta fish

Betta fish, specifically male betta fish, are the ideal candidates for life in a small display tank.

When it comes to colors, finnage, and sheer star appeal, the betta is the main attraction in any display aquarium. These fish grow to around 2 inches long when mature, making them the ideal size for a 2.5-gallon tank.

However, you should not keep a betta in a bowl or vase without a proper filtration system, a heater, and plenty of decoration and planting. Bettas are intelligent fish that need plenty of stimulation to keep them happy. And, no fish should ever be kept in an unsanitary environment with water parameters that are incorrect.

Green Neon tetras

The beautiful Green Neon tetra is a tiny fish that doesn’t grow to more than a half-inch long.

Neon tetras are brightly colored, active little fishes that should ideally be kept in shoals of five or more individuals and preferably in a large aquarium to show them off in their full glory. However, a few Neons in a small tank still make a very attractive display.

There are many species of tetras, including Neons, Black tetras, and Harlequin tetras, to name a few. These are peaceful fish that usually get along well together.

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Corydoras catfish

Corys are a staple addition to any tropical tank setup. The Cory catfish is best kept in small groups of three individuals, and you could get away with keeping a school of them in a small aquarium.

There are several different species of Corydoras catfish to choose from, and these characterful, charming little fishes make a great choice if you want a fish with personality. Also, Cory catfish are primarily bottom-dwellers, and they can be helpful in the tank by eating detritus and uneaten food that falls into the substrate.

White Cloud Mountain Minnow

The White Cloud Mountain Minnow is a tiny, peaceful fish that can add a splash of color to a small tank, especially if kept in a small school of up to six individuals.

The minnow’s natural habitat is mountain streams, where the water is cool. For that reason, this species can live happily in an unheated tank, which is good news for you if you don’t want the additional expense of buying a heater for your setup.

Rosy Red Minnows

Rosy Red Minnows are a “feeder fish.” That means that these little fishes are primarily raised and sold in the pet trade as live food for larger fish species.

That’s a shame, as these are extremely pretty fish that can make a great fish for small aquarium living. Although the species prefers a water temperature of around 70o Fahrenheit, they can survive in much lower temperatures than that and would, therefore, be quite happy in an unheated tank at room temperature.

Clown Killifish

The entertaining and attractive Clown Killifish grows to just 1.2 inches in length, making the species a good choice for a small fish tank.

These brightly-colored, stripy fish are perfectly suited to life in a micro or nano aquarium. They are easy to care for, although the Clown Killifish is a tropical species, so you will need to provide a heater. Use plenty of plants in your tank decoration scheme so that these shy fish have somewhere to take shelter when they need to.

Black Molly

The Black Molly is a lively, popular fish that many hobbyists include in their community setup.

Mollies, as a species, come in a wide range of bright, fun colors, although pure black is the most popular. Mollies are a tropical species, so you will need a heater for your mini aquarium. However, provided you make sure that the water quality in the environment is good and that oxygen levels are satisfactory, these fish will breed!

Mollies are livebearers, and with only a few individuals in the tank, there’s a good chance that you will discover fry swimming around on a regular basis.

Zebra Snails

Zebra Nerite snails can make a fun pet to keep in a small aquarium, especially if the tank is your kids’ responsibility, and the snails are pets.

Although Zebra snails do need clean water, they are not as tricky to look after as many species of fish, and they have the added advantage of being algae-eaters. So, your snails not only look very attractive with their brightly-colored stripy shells, but they also clean unsightly algae from the glass walls of the fish tank and eat leftover food and detritus that gathers in the substrate.


Shrimp are an often overlooked species of invertebrate that can make the perfect addition to a small fish tank.

These industrious little creatures are great cleaning up algae, leftover food, and general detritus, helping to keep the environment clean and tidy. Also, because dwarf shrimp species are so tiny, you can keep a group of individuals in a tiny tank without worrying about their welfare.

That said, your tank still needs a power filter, plants, lighting, and a heater. Also, as with any living creature, you will need to carry out regular water changes and filter maintenance tasks to keep the environment healthy for the shrimp.

Zebra Danio

The Zebra Danio grows to a maximum size of 2 inches in length and can make an attractive, entertaining candidate for a small fish tank.

These are tropical fish, although they do prefer cooler water conditions, so they would probably be happy in an unheated tank provided it was placed in a warm room. The one downside of the Zebra Danio is that these are confirmed schooling fish that should be kept in groups of at least six individuals. That means you would need to have a larger tank of at least 10-gallons, preferably more.

Final thoughts

Just because you don’t have a huge place, that doesn’t mean you can’t enjoy the many benefits that fishkeeping brings.

Many different research studies have shown that keeping fish is great for your physical and mental health, including for children with conditions such as ADHD and autism and seniors who suffer from many forms of dementia and Alzheimer’s Disease.

When choosing a 2.5-gallon fish tank, keep in mind that the fish’s welfare is paramount. Make sure that the tank has an efficient power filter, lighting, heating if necessary, and is big enough for the fish species that you want to keep.

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