Fish & Aquariums Freshwater Fish & Aquariums Freshwater Fish Breeds

12 Large Fish for Freshwater Aquariums

Have a tank with plenty of space? Try one of these large fish.

Two silver arowana in a planted aquarium

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Have a large aquarium with lots of room and a super-sized filter? Then you need some large fish for your freshwater aquarium. And by large aquarium, we mean at least 200 gallons and above, although you will need even more room for some of these fish. Typically, the bigger the fish, the more fussy they are about their environment and diet, so do your research before bringing any of these species home. If you have any little fish in the tank, they may become snacks since most big fish grow from eating smaller fish.

Here are 12 large fish to consider for your freshwater aquarium. Be aware that many fish stores will sell juvenile specimens of these fish that have not attained their adult size. Be sure you know how large a fish will grow before you buy it, to determine if it will fit in your aquarium and be compatible with your other fish when it matures.

  • 01 of 12

    Silver Arowana

    Two silver arowana in a planted aquarium

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    Our first fish for our large freshwater species list should come as no surprise. The Silver Arowana, Osteoglossum bicirrhosum, is a fascinating fish and can grow up to 3 to 4 feet long. These fish are highly aggressive and need lots of room to swim. A 300-gallon tank would be a good place to start, but arowanas in general are surface hunters, so they will likely ignore any space below the first 2 feet of your surface water. Any bright lights from passing cars or your TV late at night can make this fish jump for the surface, anticipating a meal, leading to injury and even death. Be sure you have a tight-fitting lid and keep all reflective surfaces far away.

    Arowanas are carnivorous, surface feeders. They are excellent jumpers and have been seen leaping more than six ft (almost two meters) from the water surface to catch insects and birds from overhanging branches in South America. Silver Arowanas will eat live prey, including fish and invertebrates, but can adapt to eating pellets, which will decrease the chance of them getting sick from eating too many goldfish or minnows as their main diet.

    Arowanas can get "droopy eye" from looking down when a surface predator is made to hunt for food at the bottom of their tank. Feeding floating pellets and frozen foods will allow it to eat at the surface. Eye drop can also occur if the bottom of the tank is bare glass, forming a reflective surface that the fish looks down at, so use dark gravel on the tank bottom. Injuries to the eye also occur if the arowana tries to jump out of the tank, so a solid, not transparent glass, cover on the tank is essential.

    Because they are aggressive carnivores, any other fish in the tank with them may be eaten. Silver Arowana are happy being solitary fish, so no tankmates can be recommended. There are other Arowana species from Africa, Asia and Australia that are protected, so be sure you have the correct species of Arowana before bringing one home. Only the South American silver Arowana is imported into the USA.

  • 02 of 12

    Banded Leporinus

    Two banded leporinus in an aquarium

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    The Banded Leporinus, or Black-Banded Leporinus, Leporinus fasicatus, is a vivid yellow-colored fish with distinctive black bands along their sides. These fish can grow up to 1 foot long and require at least 75 gallons to call their own. They can be kept in small schools, but ensure that all individuals are approximately the same size. Banded Leporinus have been known to pick at smaller individuals in a school. If one starts to fall behind the others, it is recommended to remove the fish, fatten it up in a quarantine tank. When it is the same size as the other fish, remove all the individuals from the tank, and then add them all back into the tank again, so they have to reestablish their hierarchy and won't pick on the fish being added back to the school.

    Being omnivorous, the Banded Leporinus will enjoy a wide variety of foods. They like snacking on live plants, so if you have any in your aquarium, do not get too attached as they may get eaten. Since they jump for bugs in the wild, your aquarium will need a solid lid, probably with additional weight due to the size of these fish. Like the Arowana, avoid any reflective surfaces that may mimic bug movement and cause them to jump, potentially injuring themselves.

  • 03 of 12

    Goldfish

    Goldfish in an aquarium

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    Most goldfish are kept in environments that are too small for them. A comet goldfish, Carassius auratus, can grow up to the size of a dinner plate (16 inches) and requires at least 50 to 100 gallons per fish. They stay small in small tanks and bowls because their bodies send out stress hormones, telling them to stay small. This not only results in stunted size but a stunted immune system as well, resulting in lots of illness.

    Thankfully, given enough room, goldfish make amazing pets and are very easy to care for. They eat most commercially available pellets and can tolerate a wide variety of water quality parameters. They can live up to 20 years of age and get along with many other fish species, provided they also like a temperate (not heated) environment. Goldfish do well in water temperatures in an aquarium from 60°F to 75°F. In an outdoor pond, if it is at least three feet deep so the ice doesn't freeze the water solid, they can survive in the warmer water under the ice during the winter. The water pH ideally should be between 7.0 and 8.4. Rapid changes in temperature or water chemistry can be harmful, if not fatal to goldfish.

  • 04 of 12

    Suckermouth Catfish

    Suckermouth catfish on gravel aquarium bottom

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    The Suckermouth Catfish, otherwise known as the Common Plecostomus, Hypostomus plecostomus, is very common in the aquarium trade. Given their large size, you will need at least 75 gallons for your Suckermouth Catfish. Your tank dimensions should be longer than 24 inches in both length and width in order to accommodate their body size, given its extra-rigid nature. It is not uncommon for Suckermouth Catfish to have spinal disorders from being in small tanks for too long. These fish enjoy warmer water, so they will require some sort of heater in their tank.

    The Suckermouth Catfish is a very peaceful species and may eat algae in your tank and can be fed a herbivore pellet. However, this will not keep them from eating anything delicious that floats down to them, including pellets intended for other fish. They typically will enjoy a nice log or tunnel to hang out in and get along well with most other fish since their armor coating protects them from potentially aggressive species.

    There are many other species of plecostomus besides the common plecostomus that don't grow as large. If you have an aquarium of 20 gallons or more, you may be interested in the rubber lip plecostomus or the bristle nose plecostomus, which only grow to 5 inches long.

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  • 05 of 12

    Black Ghost Knifefish

    Black ghost knifefish in a planted aquarium

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    The Black Ghost Knifefish (Apteronotus albifrons) is an odd-looking fish with a blunt face and long, tapered body with a full-body-length pelvic fin. They are a true bony fish, although they resemble an eel in body appearance. They are tapered to a point toward the tail, hence their "knife" name. Typically, these fish will be black overall with a white band or speckles at their tail peduncle.

    A timid fish, the Black Ghost Knifefish likes places to hide, commonly called a "ghost tube," where they can relax throughout the daylight. At dusk, they will come out to feed, utilizing their weak electrical sense to locate food. There is no risk of these fish causing injury to their caretakers or tankmates due to their very low electrical activity.

    The Black Ghost Knifefish can grow up to 18 inches long and requires at least 150 gallons per fish. They can get along with larger freshwater fish, but smaller fish such as guppies or neons may be considered food. Carnivores like the Black Ghost Knifefish will require a diet of carnivore pellets, chopped worms and meaty frozen diets.

  • 06 of 12

    Jaguar Cichlid

    Jaguar cichlid Parachromis managuense in an aquarium tank

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    The Jaguar Cichlid (Parachromis managuense), also known as the Aztec or Managuense Cichlid, is a very aggressive member of the South American cichlid family. These fish can easily grow over 12 inches long, and some have grown up to 24 inches. Like a jaguar, they have a pale gold body with many small black spots, with the spots being more vivid in males than females.

    As a South American cichlid, the Jaguar Cichlid is a hardy fish and can tolerate a wide variety of water quality parameters. They will attack and eat any smaller fish, so the only tank mate that may be appropriate, provided you have a fish with a good temperament and similar size, is an Oscar or other large cichlid.

    The Jaguar Cichlid is an omnivore that is well suited to a varied cichlid diet, including pellets, frozen treats and vegetables. Given their aggressive nature and large size, you will require at least 75 gallons per fish, with over 24 inches in width and length in order to allow a fully grown fish to turn comfortably.

  • 07 of 12

    Tiger Catfish

    Tiger shovelnose catfish along rocky wall

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    The Tiger Catfish (Pseudoplatystoma tigrinum), otherwise known as the Tiger Shovelnose Catfish, can top out at over 3 feet long. Native to rivers of South America, this catfish species has a tan to brown body with multiple black bands along their body with superimposed lighter speckling, giving them their tiger-like appearance.

    Due to their very large adult size, you will require at least 200 gallons per Tiger Catfish. These fish are very active, requiring lots of free swimming space and are known for jumping to catch potential prey, so a tight-fitting, weighted lid is required. They enjoy a variety of larger décor items in their tank, just keep in mind that these are large, active fish and will redecorate as they see fit.

  • 08 of 12

    Tire Track Eel

    Tire track eel on an aquarium plant

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    The Tire Track Eel (Mastacembelus armatus) is not a true eel, but has an eel like appearance. It enjoys burrowing in soft aquarium substrate. Also known as the Spiny Eel, Zig-Zag Eel, or Marbled Spiny Eel, this fish has an elongated brown body with lighter brown spots along their sides. Take care when handling this fish, since they have numerous spines along the top of the body cranial to their dorsal fin.

    Because they like to dig in substrate, the Tire Track Eel will require a soft substrate, such as sand or small gravel. They may uproot any plants, and topple décor items you have resting on the bottom of your tank. Growing up to 30 inches long, the Tire Track Eel will require at least 125 gallons per fish and substrate at least 2 inches deep to cover their body. They like having a little bit of salt in their water, but not at a level that would be considered brackish. Tire Track Eels enjoy having live plants but will continue to uproot them.

    Being bottom dwellers, the Tire Track Eel feeds on a variety of sinking pellets, live and frozen foods. They will also eat small fish in their tank, so be sure to only keep them with suitable larger fish, but not any that will pick on them.

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  • 09 of 12

    Ornate Bichir

    Ornate bichir Polypterus ornatipinnis resting on gravel aquarium substrate

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    A member of the primitive fish family, Polypteridae, the Ornate Bichir (Polypterus ornatipinnis) has the unique ability to survive out of water using its lung-like swim bladder adaptation. The Ornate Bichir has a pale belly with mottled black and yellow patterns along their body. They can grow up to 24 inches long and require up to 100 gallons per fish. They are prone to jumping, given that they can survive for a short period out of water, so a tight, weighted aquarium lid is required.

    The Ornate Bichir is a semi-aggressive species that does not like having other bichirs in the same tank. They are also very fond of eating smaller fish, but do well with larger aquarium fish. Bichirs are bottom-dwelling fish, so one should be kept with other fish that swim in the middle or top areas of the aquarium, and not have to share space with other bottom fishes.

    A primarily nocturnal fish, your Ornate Bichir will likely hide during the day in a cave or densely planted area. Some Ornate Bichirs can be kept with other individuals, but some do not get along and will need to be the only bichir in the tank. They are captive-bred and are easy to feed a variety of fish food options, such as sinking pellets and frozen food.

  • 10 of 12

    Bala Shark

    Bala shark Balantiocheilos melanopterus in an aquarium with plants

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    The Bala Shark (Balantiocheilos melanopterus) is a member of the Cyprinid family and can grow up to 14 inches long. This fish is known for their large silver body with black eyes and fin tips. Like goldfish, they are hardy aquarium fish and do well in a school, but grow considerably larger than most fish owners realize.

    A schooling fish, the Bala Shark prefers to have a small group of individuals in one tank. You will need at least 3 or preferably more that will require at least 125 gallons per small school. They get along well with many other freshwater community fishes and prefer heavily decorated or planted tanks. The Bala Shark is a hardy species with a wide range of water quality parameters and suited to many commercial diets.

  • 11 of 12

    Fahaka Puffer

    Fahaka puffer Tetraodon lineatus in aquarium

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    A true pufferfish of the family Tetraodontidae, the Fahaka Puffer (Tetraodon lineatus), is a brown and tan striped fish that can grow up to 15 inches long. They can be very aggressive and do not get along with other fish and will eat any crustaceans or invertebrates in the aquarium. Therefore, they will need to be kept in their own tank of at least 125 gallons.

    The Fahaka Puffer is a very fun fish to have and interact with. They are picky about their water quality and like having a lot of décor in their tank. Like other puffers, they have a strong beak used for crunching up shells of mollusks and bivalves, so ensure to include these in their diet. If they don't wear their beak teeth down from chewing on mollusk shells, the teeth can become overgrown and may need to be trimmed.

  • 12 of 12

    Needle Nose Gar

    Needle nose gar Xenentodon cancila in planted aquarium

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    The Needle Nose Gar is a uniquely shaped fish with a long, slender body and a large mouth full of pointy teeth. They can produce very quick bursts of speed to chase after smaller prey fish, and grow up to 15 inches long, so they will require at least 75 gallons. Most of the décor in their tank should stop at mid-tank level in order to allow them lots of free swimming space above.

    Although they may look docile, the Needle Nose Gar is a speedy predator and will easily snap up any smaller fish in the tank. They can only be house with aggressive fish of similar size, and can be kept with additional individuals of the same species. They are strict carnivores and require a variety of live foods, including crustaceans.

    These fish are known for biting human hands in the tank, so take special care when working with these fish. Needle Nose Gar teeth are very sharp and they are keenly aggressive, so be aware.

Notice anything not on our list? If you guessed "pond fish," such as koi, there is good reason they are not on this list. Koi require at least 250 gallons per fish, and need at least 3 in a school, therefore, they are not suitable for indoor aquariums. Yes, they start out small, but they can easily grow larger than most of the fish on this list and need to be given adequate space or they will easily get sick from stunting. Female koi have grown over 39 inches (1 meter) in length.

As with all of these species, enough space is critical to maintain their overall health and wellbeing. Although they all start small, you will need to take into account how big they could potentially grow. It can be very difficult to rehome a fish that has run out of room in your tank, so plan for the inevitable and ensure your tank will hold their full adult size. As with any new fish, do your research to ensure they will be happy in the home you are providing them with adequate filtration and proper diet.