5. Oscar

OscarOscars are thought to be one of the most intelligent aquarium fish available, and are one of the few species that can be trained to do tricks.

Oscars however are not a community fish, they should be kept in a species only tank, and they can grow very large, very quickly.

They require a lot more maintenance than other fish, due to their carnivorous nature and the amount of waste they create.

On the positive side, they are one of the few species you can hand feed; they will often eat food from between your fingers. Oscars thrive when kept in pairs, or group of 5+, and should be housed together from a young age.

6. Mollies

Black MolliesThis small, peaceful species grow to around 3-4 inches, and adapt well to a variety of water conditions.

The ideal tank conditions are: a minimum tank size of 20 gallons, and warm water with a pH between 7.0-7.8.

Mollies are omnivorous, and will require a diet of both plant and animal food.

Interestingly, they are livebearers, meaning they give birth to their young live, rather than lay eggs. Mollies are very easy to care for, but they also breed very easily, so if you’re a beginner you might want to keep just a single sex.

7. Zebra Danios

Zebrafish (Danio)The Zebra Danios make the perfect beginner fish, they are very easy to care for and can grow up to 5-7cm.

They should be kept in at least a 10 gallon tank, in groups of at least 5. Danios are a schooling fish and will become stressed if their numbers are too lows.

They are not fussy eaters and will eat most foods; the healthiest option for them would be lots of worms, insets and crustaceans to mimic their natural diet, however a good quality flake will also work with a supplement of frozen or live food.

Danios are also known to jump so you may want to keep your tank covered!

8. Platies

Sunburst Platy
Sunburst Platy

Platies come in almost every color imaginable and they are very easy to care for – just two of the reasons why they are so popular.

They are a great community fish, they’re very peaceful and get along well with guppies and mollies.

Although small, platies are very active and love being in groups. A 10 gallon tank is large enough for 5 fish.

Whilst they are omnivorous, they do require much more herbivorous food, than meats. Ideally, they need a good mix of plant based food and proteins.

9. Cherry Barb

Cherry BarbThe Cherry Barb gets its name from the color the male turns when it is spawning. Usually, they are silver/black with a golden lateral line.

They are a peaceful fish which will grow to around 2 inches in length, and they require a minimum tank size of 25 gallons. Cherry Barbs are omnivorous and will eat most types of food including live, fresh, frozen and flake foods.

They are easy to care for and can be kept in community tanks with open space to swim, but also planted areas where they can hide.

10. Pearl Gourami

Pearl GouramiThe Pearl Gourami is a relatively large, but peaceful fish and one of the most easy to keep Gouramis.

The minimum tank size for this species is a 30 gallon tank with plenty of hiding places, dark substrate and low lighting.

They can be housed with other fish of a similar size and temperament; however you should not house them with aggressive fish.

Pearl Gourami’s are omnivorous and should be fed algae-based foods and meaty foods.

They are well known for eating Hydra, a tiny pest that has tentacles with venom, so make a great solution if you have a hydra problem.

11. Swordtails

SwordtailThe swordtail is similar in shape to platy and guppy fish, with a slightly bulkier body, and a sword shaped extension of its fin.

There are many different color variations available and they are quite hardy which makes them a perfect species for the beginner aquarist.

Swordtails are usually peaceful, yet lively. They thrive in community tanks, and like to swim in loosely grouped schools.

They breed easily, and if you do decide to breed them, you should keep them away from their parents; Swordtail parents will often eat their fry.

12. Discus

DiscusThese beautiful and graceful fish can grow to be quite large, and therefore require a larger tank, a minimum size of 25 gallons.

Discus are not recommended for beginners, and instead should only be kept by experienced aquarists.

They can be housed with other fish that require the same water conditions, as long as they are not aggressive.

Discus will take a variety of foods but are carnivorous in nature. The best diet for them consists of beef heart and blood worms supplemented with flakes to provide vitamins and minerals.

13. Killifish

The Blue Lyretail Killifish

Killifish come in a wide variety of bright colors. They are extremely hardy fish, and there are over 700 species – a breed to suit almost every tank condition.

They are generally peaceful fish and do well in community tanks with other small, non-aggressive fish. It’s best to keep just one male to each tank though, because they can be aggressive towards each other.

Killifish are very easy to breed, and are either annual or non-annual breeders. In the wild, annual killifish lay their eggs in temporary bodies of water which dry up for months at a time. When they refill, the fry hatch.

Most Killifish are carnivores and therefore enjoy a diet of insect larvae, worms and crustaceans.

14. Bettas

BettaAnother extremely popular freshwater fish is the Betta. It’s not surprising why; Bettas are vibrantly colored, and easy to care for.

Male Bettas are notoriously aggressive towards other males. Therefore only one male Betta should be kept in each aquarium. They can be housed with other peaceful fish.

Bettas require an omnivorous diet, of both plant and animal foods. It is one of the Best Fish For Small Aquarium.

They grow to a maximum size of 3 inches. Although you often see Bettas in small ornamental tanks, they should be housed in larger tanks.

Did you know: Bettas are able to breathe air outside of the water due to their labyrinth.

15. Plecostomus

Sailfin Pleco
Sailfin Pleco

Plecs are a breed of catfish, they have heavy armored plates on their bodies, and sucker-shaped mouths to feed on the algae in your tank.

Whilst some species are happy eating algae, wafers and flakes, others will need meaty food such as frozen brine shrimp.

Breeding Plecs is extremely difficult and only a small number of aquarists have managed to breed them.

Plecos can live for 20 years, sometimes longer if cared for correctly. It’s also worth knowing that they can jump too – so keep a lid on your tank.

They can be housed with many different species, but avoid keeping them with fat/flat bodied fish such as goldfish as they may suck on them.

16. Rainbowfish

Boeseman’s Rainbowfish
Boeseman’s Rainbowfish

Rainbowfish originate from Australia and Southeast Asia. They are a peaceful schooling fish that can grow up to 6 inches long.

This is perhaps one of the least common fish that we are featuring here, perhaps because its colors only begin to show as they enter adulthood…

However, if given the right care, in just a couple of years they can display stunning and vibrant colors.

Rainbowfish get along well with other upper level schooling fish such as danios, bards and larger tetras.

17. Corydoras Catfish

Corydoras CatfishAlso known as Cory Cats, these fish are a staple in most freshwater tanks. They’re easy to care for, calm and peaceful yet active bottom dwellers.

They are very social, and whilst you can keep them individually, they thrive if kept in a group of two or more.

They get on well with most community tank fish as long as they are not aggressive.

Corydoras grow up to 2.5 inches in length, and are excellent tank cleaners. They’ll pick up left over foods from the gravel but also require other foods such as flakes and bottom feeder tablets.

18. Goldfish

GoldfishWhen most people think of Goldfish, they think of small fish bowls with a fish that was won at the fair. This is not the correct way to house goldfish.

Few people know that they can actually grow up to 14 inches in the wild.

The minimum tank size for a goldfish is 20 gallons, you’ll also need a filter and to perform 10-15% weekly water changes.

There are many different varieties of goldfish, and its fine to mix them as long as they aren’t breeds that would compete with each other for food. For example, keep single tailed varieties together and normal eyed goldfish together.

20. Angelfish

AngelfishAngelfish are a member of the Cichlid family, which also includes Discus, Oscars and Parrot fish, all common fish amongst aquarium keepers.

They can grow up to 6 inches in length, 8 inches tall, and come in a variety of colors and patterns.

They are omnivorous, so will need a balanced diet of meat and plant food. It is one of the Best Fish For Small Aquarium.

Their tank should be at least 20 gallons, and the water should be slightly soft and acidic.

As they mature, they can become aggressive, especially if your tank in overcrowded. In general though, they are a good community fish, just don’t keep them with very small fish or fin-nipping species.

Advice on Setting Up Your New Tank And Selecting The Best Fish For Small Aquarium

Caring for Your Fish

Keeping fish is a rewarding experience. Unfortunately, too many people see tropical fish as disposable pets and don’t fully consider their needs.

Please do not overstock a small tank, or add fish that are clearly unsuitable. This is bad news in any tank, but especially in smaller tanks things can quickly spiral out of control.

There are a few things you might want to think about before choosing such a small tank.

For one thing, you are typically unable to choose your own aquarium filter for many mini tanks are very weak, and only slightly better than none at all.

Often it’s a poor under-gravel system: Just an air pump pushing bubbles through an air stone lodged in a tube which creates a current that will hopefully suck debris down into the substrate.

All tanks require regular water changes, but this type of filtration requires frequent cleaning, probably to the point of removing the gravel once a week and rinsing it.

In such a small tank any waste can build up to dangerous levels very fast. But if you’re willing to put up with the work, at least the bubbles serve to oxygenate the water.

These tanks also rarely come with heaters, a must for tropical fish. If the air temperature in your home is steadily in the mid-70s you don’t need a heater, but otherwise, your choices of fish are limited.

The light that comes with the tank will warm the water somewhat, but not nearly enough in cooler environments.

Remember that by choosing to keep fish or any animal, you are entering into a contract as its steward and caretaker. Your fish are completely dependent on you to care for them in a humane manner and to make sure their needs are met.

Sure you’ll make mistakes, and you’ll probably feel badly when you lose a fish because of something stupid you’ve done. But we’ve all been there. There is a difference between making an honest mistake and willfully endangering an animal.

If possible it’s best to upgrade to a larger tank, at least ten gallons, that can better meet the needs of your fish. But if you are set on a small aquarium be sure to choose your fish wisely, and take good care of the tank. You’ll be a happy fish keeper, with happy fish.

Are Goldfish Good for Small Tanks?

Goldfish are generally not a good choice for such a small tank. Most goldfish grow much larger than you may realize, and they need more space than a tiny tank.

They are also dirty fish, and will quickly pollute such a confined environment. That said, if you have to choose between keeping a goldfish in a bowl or a 3-gallon tank, the small tank would obviously be the better option.

Goldfish grow much larger than many people realize and are not a good option for small tanks or bowls.


If you’re new to fishkeeping, I recommend starting slowing and adding just a few fish at any one time. This will give you chance to get to know and understand how to select the Best Fish For Small Aquarium and care for each species of fish before you add another.

Make sure you always research the species you want to buy to ensure you can give them the time and care that they require.

This article should only serve as an example of the popular types of freshwater fish, rather than a guide on how to care for each one. For guides visit our breed care guides here.

Do you already keep fish, or are you just starting out? Which one would you say is the most popular species?