The 11 Best Large Freshwater Fish for Aquarium Keeping

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Setting up a big fish tank opens up all sorts of exciting possibilities.

Discus Fish (Symphysodon)

This allows you to finally include some of the large freshwater fish you’ve always dreamt of into your community aquarium.

However, the increase in tank size also comes with the burden of choice.

Since each fish species has its own unique behavior and requirements you’ll need to think carefully before adding them to your tank.

In this article, I’ve gathered some of the biggest freshwater fish for a freshwater aquarium along with a summary of their needs and behavior.

The Best Large Freshwater Fish for Aquarium Keeping

Since the term large is fairly subjective, I decided to use a measure of 8 inches as a starting point for the species on this list.

Most fish with this size typically require at least 55 gallons of water to thrive which is quite substantial.

However there are a few fish species of this size that can also fare well in a smaller 40 gallon tank.

Having said that, it’s time to take a look at some of the best large freshwater fish for an aquarium:

Gold Severum

A gold severum swimming near a plant leaf

by addywoot

  • Maximum body size: 8 inches (20.32 cm)
  • Minimum tank size: 40 gallons
  • Water temperature range: 73°F to 84°F (22.7 – 28.8°C)

Coming first on this list is the gorgeous Gold Severum (Heros severus). This moderately sized cichlid can grow up to 8 inches which makes it the biggest pet fish you can keep in a 40 gallon tank.

In terms of behavior, the Gold Severum is fairly peaceful and can get along with similarly sized and well mannered fish.

They will however eat smaller fish so you should avoid housing them with barbs, danios, tetras or other small species.

Apart from its peaceful disposition, the Gold Severum is also a relatively hardy fish so it’s perfect for beginners.

The only thing you should bear in mind is to keep them under a lid since they can jump out if they’re startled.


a bichir sitting in a crevice of aquarium rocks

by OphanimWheels

  • Maximum body size: The more popular species reach between 11 and 23 inches of body length (28 to 58.4 cm)
  • Minimum tank size: 90-gallons for a single one
  • Water temperature range: 72 to 82°F (22.2 to 27.7°C)

When it’s kept in a proper environment, the bichir can reach a massive size of 23 inches.

This makes it ideal for tank setups intended to keep “monster” fish.

And since it has a peaceful disposition, it can also be kept in a community with similarly sized fish.

Having said that, you’ll need a real estate of at least 90 gallons if you want to have these giant fish as a pet.

In case you do, you’ll need to keep in mind that despite their calm demeanor, bichirs are still predators.

Therefore, you shouldn’t house them with fish that are small enough to fit their mouth as they’ll try to eat them.

Leopard Bush Fish

a giant leopard bush fish swimming among some aquatic plants

by The_Red_Squirrel

  • Maximum body size: 8 inches
  • Minimum tank size: 30 gallons
  • Water temperature range: 72°F to 82°F (22°C to 28°C)

The Leopard Bush Fish, also known as the spotted climbing perch, is a species of African freshwater fish from the Ctenopoma genus.

In nature, these goofy looking fish inhabit slow moving rivers and streams where they hunt smaller fish, insects and crustaceans.

As such, you need to be careful when you’re choosing their tank mates since they’ll take any opportunity to take a snack.

Anyways, the Leopard Bush Fish can reach a size of 8 inches when it’s properly cared for.

However, if you want them to reach their optimal size you’ll need to provide them with ample space.

In this regard, a 50 gallon tank will meet their needs in a more appropriate manner.


a large ropefish gallantly swimming in its in aquarium

by PrKnockers

  • Maximum body size: 18 inches (45 cm)
  • Minimum tank size: 55 gallons
  • Water temperature range: 72 – 82° F (22.2 – 27.7℃)

The Ropefish from the Erpetoichthys genus is a long eel-like fish species with a calm personality and curious nature.

In the wild, it can reach a staggering size of 3 feet, but captive specimens rarely exceed 18 inches.

As you might expect, a fish of this size requires quite a lot of space to roam freely and feel at home.

As a result, you’ll need a tank with a size of at least 55 gallons to accommodate this cute oddball.

Even though they’re docile, ropefish are predatory by nature and will eat fish that can fit in their mouth.

It’s also a bad idea to keep them with aggressive fish such as plecos since this can disturb their slime coat.

With their peaceful nature and unique appearance ropefish are one of the best big fish for a 55 gallon tank.


a big oscar fish swimming near the surface of its tank

by Goddo-Fo-20

  • Maximum body size: 10 – 12 inches (25.4 cm – 30.5 cm)
  • Minimum tank size: 55 gallons
  • Water temperature range: 74 – 81°F (23 – 27°C)

The amicable personality and intelligence of Oscar fish has made them one of the most popular species in the hobby.

These South American cichlids can learn to recognize you and will occasionally come up to greet you.

They also come in a variety of color morphs and can be used as a centerpiece fish.

With that said, Oscars aren’t small by any means and can grow up to 16 inches under optimum conditions.

Most specimens however reach a maximum size of 12 inches in their adult form.

Since they’re quite large and produce a lot of waste, these tropical fish require at least 55 gallons of free space.

If you intend on keeping more than one Oscar, then you’ll need double that space and prepare a 100 gallon tank.


a mature yellow-blue discus swimming in front of a driftwood branch in its aquarium

by overseille

  • Maximum body size: 9 inches (23 cm)
  • Minimum tank size: 75 gallons or larger
  • Water temperature range: 82–88°F (28–31°C)

The Discus fish (Symphysodon aequifasciatus) has an intricate color pattern and shape which makes it extremely appealing.

However, this big round fish is also extremely difficult to care for since it requires a high water temperature and regular water changes.

If you want to keep it healthy and make its colors pop, you’ll need to provide a water temperature of 85 to 86°F.

Unfortunately, at these temperatures you’ll also have a fairly limited choice of plants.

So if you want to keep a Discus in a planted tank setup it’s best to use anubias, java fern and sword plants.

Another thing you should keep in mind is that the Discus is a schooling fish and should be kept in a school of at least 6 fish.

With that said, you’ll need at least 75 gallons of real estate since the Discus grows up to 9 inches and produces a lot of waste.

Bala Shark

two huge bala sharks keeping each other company

by HellknowsJS

  • Maximum body size: 15 inches (38.1 cm)
  • Minimum tank size: 75 gallons for a single specimen and 200 (but preferably 400) gallon tank for a school of 3 or more
  • Water temperature range: 72 to 83°F (22.2 to 28.3°C)

The Bala Shark is a great choice if you’re looking to add some shark-like diversity to your freshwater setup.

This aptly named fish can become huge upon maturity and reach a staggering size of 15 inches.

Naturally, this prompts a large aquarium setup that provides a lot of free space for roaming and water circulation.

To be more precise, you’ll need at least 75 gallons of water to keep a single specimen.

However, Bala Sharks are social by nature and do appreciate the company of their own kind.

As such, it’s better to keep them in a group of three and house them in a 200 gallon aquarium.

This will significantly improve their mood, decrease stress and keep them healthy.

You should also cover the aquarium with a lid since they might try to jump out.


a sizeable anglefish in its planted aquarium

by jack27nikkkk

  • Maximum body size: 8 inches
  • Minimum tank size: 20 gallons for a single specimen
  • Water temperature range: 78 – 86°F (24.4 – 30℃)

With their majestic long fins and splendid color pattern, angelfish are one of the most beautiful freshwater species you can keep.

Upon reaching adulthood, these gorgeous fish reach a size of 8 inches.

And even though they’re fairly big, they can be kept in tanks as small as 20 gallons.

If you intend on keeping more than one angelfish, you should keep in mind that they can get territorial during breeding.

Due to this it’s best to keep a single pair if you want to avoid any aggressive behavior.

Since their long gorgeous fins can attract unwanted attention, you should avoid keeping angelfish with fin nippers or fast moving fish.

The best tank mates for angelfish in my opinion are cardinal tetras, black tetras and cory catfish.

These species are fairly docile but also big enough to not get eaten by angelfish.

Clown Loach

massive clown loaches resting on the bottom of their planted tank

by LoSazy

  • Maximum body size: 12 inches
  • Minimum tank size: 100 gallons
  • Water temperature range: 75 to 85°F (24°C to 29°C)

True to their name, clown loaches have an amusing appearance that’s bound to catch your eye when you enter a pet store.

These cuties are also an excellent community companion due to their peaceful nature and attitude.

However, since they’re a schooling species, clown loaches do get shy when they’re kept in lower numbers.

In my experience, it’s best to have a school of at least six fish if you want to make them feel at ease.

These large tropical fish can reach a maximum size of 12 inches so you’ll need at least 100 gallons of water to keep them as pets.

Another great thing about clown loaches is that they’re excellent at dealing with pest snails.

Suckermouth Catfish

a hand holding an enormous common pleco


  • Maximum body size: 15 to 24 inches (38 cm to 61 cm)
  • Minimum tank size: 125 gallons
  • Water temperature range: 72 to 82°F (22 to 28°C)

The Suckermouth Catfish also known as the Common Pleco is a large bottom feeder with an affinity for algae.

These tropical fish can grow to a massive size of 24 inches when they’re kept on a proper diet and have enough space.

With a size that big, they’re arguably one of the biggest aquarium fish you can keep as a pet.

Even though they’re an algae eater, suckermouth catfish can’t survive on algae alone.

As a result, you’ll need to provide a balanced diet of fish pellets and fresh vegetables.

Despite their enormous size, suckermouth catfish are extremely peaceful and will get along with most fish species.

Congo tetras, neon tetras, and rainbowfish are just a few species you can have as their tank mates.

Jaguar Cichlid

a colossal jaguar cichlid swimming in its tank with a common pleco in the background

by Zecalyadon

  • Maximum body size: 14 – 16 inches
  • Minimum tank size: 100 – 125 gallons
  • Water temperature range: 73°F to 82°F (22.7 – 27.7°C)

The Jaguar Cichlid has a captivating appearance which makes it an ideal candidate for a centerpiece species.

When they’re young, these fish have a goldish hue marked by large black bands that wrap around its body.

As they age, the bands gradually morph into black spots giving them their signature jaguar appearance.

On that note, jaguar cichlids aren’t small either. Upon maturity, they can reach a whopping size of 16 inches.

Due to this, you’ll need an aquarium of at least 100 gallons to keep these monstrosities stress free.

Another great thing about the Jaguar Cichlid is that with proper care you can enjoy its company for up to 15 years.

My short recap

The number of fish species you can keep as pets when you’re not bound by space is nearly limitless.

You can keep a school of clown loaches, use an Oscar as a centerpiece species or get a Bala Shark to make your setup more exotic.

Just remember to make sure that the large freshwater fish you add to your aquarium can coexist peacefully with the rest of its inhabitants.

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Momchil Boyanov is the Founder and now Senior Editor of AquAnswers. He has over 13+ years of experience in keeping home aquariums as well as providing professional aquarium services. Momchil has had his fair share of adventures in aquarium care. He has made MANY mistakes throughout his fishkeeping journey and thus learned A LOT. Through Aquanswers, Momchil shares knowledge about freshwater and saltwater aquariums with the people within this community.

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