20 Fish Species that Are Not for Beginners


Fish Species Beginners Should Avoid

Some of the most beautiful and popular fish available for aquariums are the wrong choice for beginners. But other types of fish should do well for a beginner aquarist. As a beginner, the choice of fish to keep can get very confusing, mainly because there is little information on good fish for beginner aquariums.

This is why we have compiled a list of fish species not for beginners which will prove to be helpful. One of the benefits that come with keeping an aquarium is that it brings tranquility to your space. The bubbling water and the swimming fish can relax your mind and help you remove stressful thoughts.

Below is a list of fish that beginners should avoid in their aquarium:

  1. Giant Gourami
  2. Red Tail Catfish
  3. Flowerhorn
  4. Oscar Fish
  5. Bichir
  6. Giant snakehead
  7. Siamese Shark
  8. Bala Shark
  9. Discus Fish
  10. Asian / Silver Arowana
  11. African Cichlids
  12. Pleco Fish
  13. Red Tail Shark
  14. Alligator Gar
  15. Peacock Bass
  16. Vampire Tetra
  17. Piranha
  18. Northern Pike
  19. Wolf Fish
  20. Freshwater Stingray

1. Giant Gourami


Giant Gourami (CC BY-SA 4.0 source)

The Giant Gourami is one of the largest labyrinth fishes reaching up to 60 cm in length. Most of these species are kept in community aquariums because they require space to handle their high physical activity. Because of their size and high metabolism levels, this kind of fish eats a lot of food.

In pet stores, these fish appear to be very attractive with their pointed snout, a banded coloration, and a flat head. Young giant Gouramis have blue/gray stripes on their yellow/gold background skin. The strips are lost when the fish is growing old, and the color is replaced with a whitish color.

The reason why giant Gouramis are not the right choice for beginners is that they require extra capital to keep in the aquarium. Their adult life length can get up to 40cm plus they are highly active, and this is why they need bigger aquariums. Another thing is that they eat a lot of food and may need more experienced aquarist that will understand their feeding habits.

2. Red Tail Catfish


Red Tail Catfish (source)

A beginner aquarist might fall into the trap of buying Red Tail Catfish because it is the most attractive in the catfish family. Although it continues to be sold in the aquarium store, it is not recommendable to beginners because of its side in its adult life stage (4-6 feet). In addition to this, the Red Tail Catfish grows very fast. Having a lifespan of 15 years, one should consider if they can handle this kind of fish and we do not recommend this fish to beginners.

Ted Tail Catfish can be as small as 5cm when they are young and displayed in the aquarium store. They have long whiskers like cats on the mouth, have a red tail, and they are colorful even in their adult life stage. As a beginner, one should not fall for this fish because it is aggressive, and depending on its size and a beginner may not be able to handle its aggressive behavior.

Another reason beginners should avoid this fish is that it requires a large tank that can handle 1000 gallons or be at least 12X4X3 foot. Professional aquarists mostly keep this type of fish because of its picky eating behaviors.

3. Flowerhorn


Flowerhorn (CC BY-SA 4.0 source)

Flower horn is a special kind of fish with an exciting temper, unusual appearance, and behavior. They change their appearance color during their life cycle stages, so if one is interested in buying a particular color, they can only choose from mature Flowerhorn.

From the facts above, one might seem to assume that the Flowerhorn is the right type of fish for beginners, but it’s not. The first reason is the fish requires a large and spacious tank because its length is 30-40 cm in its adult life. They grow up to 2cm a month and need lots of food during their development.

In most cases, Flowerhorns are very aggressive and territorial and thus requires that one keeps this type of fish alone in their tank. It is not advisable to keep it with tank mates or plants as it can attack and bite other species of fish. For the beginner who would be interested in mixing various species of fish in one tank, it is essential they consider avoiding the Flowerhorn.

4. Oscar Fish


Oscar Fish

Oscar fish are infamous for being aggressive and territorial in aquarium tanks. They fight other fish for food and space, which is hard to imagine considering their elegant swim style. Beginners can be convinced by their colorful appearance and different social behaviors.

Beginners should leave this type of fish to more experienced aquarists. Oscar fish require a right set up the tank and the right tank mates which requires some experience to find out. Also, to control their aggression requires one to understand the right conditions for the Oscar fish such as water temperature, feeding behaviors, and choosing the right tank mates for this type of fish.

A small tank will also cause aggression from the Oscar fish, and they generally require a larger tank that can fit 30-50 gallons of water. A small tank will cause stress, assault, and frequent illness to the Oscar fish.

5. Bichir Dragonfish


Bichir Dragonfish

Birch is of irresistible beauty with its diamond-shaped scales plus its archaic look. The fish looks more of a shark expect for its smaller size. It has a kind of Polypterids skin that seems to act as armor against other predatory fish.

The only reason newbie aquarist should not consider keeping this fish is that its size. One thing to consider is that this is a predator fish and newbie aquarists may not be able to choose appropriate tank mates for this type of fish. When kept with other fast fishes, the Birch might starve because they are generally slow in their ways of finding food.

Other complex requirements include the high activity of the fish can cause it to jump off the tank. This means that Birch requires a deep, spacious tank with a lid and sufficient air, particularly considering the fish can grow to a length of 70cm.

6. Giant Snakehead


Giant Snakehead (CC BY-SA 4.0 source)

Giant Snakehead gets their name from their flattened shape and scales on their heads that look similar to those of most snakes. They also have long anal and dorsal fins which run along with their bodies. Their colors are mainly grey, brown, black, or white, and they are pretty attractive.

However, this type of fish is not recommendable to a beginner aquarist because they can grow huge up to a foot or two. They have a demanding nature and are mostly kept at a community aquarium by experienced aquarists. Giant snakeheads are territorial and aggressive, meaning that one has to choose their tank mates in a precise manner. This type of fish is fiercely carnivorous and can attack and feed on smaller fish if not sufficiently trained to accept dead or frozen food.

7. Siamese Shark


Siamese Shark (source)

This is a large predatory fish and is also known as sutchi catfish or iridescent shark. It is from the catfish family with a Thailand and Southeast Asia accent. Their color is silver with a dark dorsal side, which is a color that favors their appearance.

Iridescent sharks are timid and easily scared and not suitable for beginner aquarists. Experienced aquarists place the iridescent shark in quiet and serene places to prevent the fish from developing stress. Keeping this type of fish requires experience in handling fish because it is likely to be harassed by big fish, and then it is expected to feed on other small fish.

Siamese shark thrives in deep waters and thus requires a large and deep tank to handle its size and activity. This may prove to be expensive for first-time aquarists plus this fish has a complex personality for the beginner to comprehend.

8. Bala Shark


Bala Shark (source)

The Bala Shark can make a great addition to your aquarium as it is a beautiful and a great tank mate to other types of fish. It is a shoaling fish, which means that it likes to live and swim in groups of other Bala fish. It comes in multiple colors, which include gray, black, and yellow. Due to its adult size of up to 40 cm, we do not recommend this type of fish to a beginner aquarist.

Keeping Bala fish might prove to be expensive for a beginner aquarist because it requires a minimum tank size of 150 gallons of water. One is also necessary to keep 4-6 Bala fish because of its shoaling nature. Apart from these, the fish is peaceful and easily fits with other types of fish in a tank.

9. Discus Fish


Discus Fish

Beginners might be dumbfounded by the colors and beauty of the Discus fish, but it might come at a hefty price. They are commonly known as the queen of the aquarium because they need a special kind of treatment. The fish requires loyal treatment as it is a shoaling fish and expects to be kept in groups of 6-8 Discus fish. The high cost of this fish plus for its maintenance calls only for experienced aquarists.

It is, however, not aggressive, and they are shy but living alone without other Discus fish will stress them out. They require a tank size of 80-100 gallons of water as the fish are highly active. Discus fish is not recommendable for beginners because it is expensive and requires one to purchase 6-8 discus fish for shoaling.

10. Asian / Silver Arowana


Asian Arowana (CC BY-SA 4.0 source)

While the Asian / Silver Arowana is generally a beautiful fish, it is not recommendable for a beginner to keep this kind of fish. It grows to up to 3 foot in length; it is carnivorous and has a behavior of being semi-aggressive. It has a short tail fin, sharp dorsal fins that run across their bodies, and a silver-like scale-covered body.

The fish might deem difficult for a beginner to keep because of its size, which requires a large tank of up to 250 gallons. The Silver Arowana is a notorious jumper and needs someone with experience on how to handle such fish. These kinds of fish are strong and aggressive swimmers, and for this reason, they require large aquarium tanks which might be expensive for a beginner to maintain.

11. African Cichlids


African Cichlids

African Cichlids are known to add color to an aquarium with each fish having a different kind of pattern and coloration. The fish are infamous for being the most colorful, so there will always decorate your tank. They have a friendly and social personality and grow to a maximum of 8 inches. However, these types of fish are not suitable for beginners, as they are more aggressive and bigger.

The African Cichlids are always looking for food and might make you think you are underfeeding them. It requires an experienced aquarist to note their feeding habits. During their mating season, the African Cichlids might become territorial and aggressive to the point of killing other small fish in the tank.

Another reason beginners should not keep African Cichlids is that their behavior of always searching for food is scavenging and destructive of the decoration in the tank.

12. Pleco Fish


Pleco Fish (CC BY-SA 4.0 source)

Pleco Fish are a group of armored catfish, and they grow up to 24 inches in length. This type of fish is generally peaceful and comes in gray and brown colors. Majority of Plecos are brown with other having sand colored spots and patterns. They have a behavior of being timid during the day and active at night time. They are omnivorous fish, but they require experienced aquarist who understands their feeding habits.

For their appearance, they are considered armored fish because of their boney plates covered body. Although the fish are generally small, they require high levels of care and maintenance, which might be unknown to beginner aquarist. Also, the Pleco Fish needs someone with experience on how to handle timid and shy fish species from their preferred habitat environment, social activity, and feeding habits.

13. Red Tail Shark


Red Tail Shark

Red Tail Shark sort of resembles a shark and thus its name. They have black bodies with a red tail and quite a beauty to add to the aquarium tank. Unless one can afford a big tank, Red Tail Shark is not recommendable for beginner aquarists. The Red Tail Shark fish are known to be territorial and aggressive to the point of fighting other fish varieties in the tank. When kept with Rainbow Sharks, the tank can turn to a war zone between the two species.

Newbie aquarist cannot handle the Red Tail Shark because of its dominant personality and chases other species around the tank all day. The fish grow up to 15 cm but one reason why beginners should not consider it is because they can’t handle its aggressive and bullying behavior.

14. Alligator Gar


Alligator Gar

The Alligator Gar is one beautiful fish that one cannot ignore when shopping around for pet fish. With its patterned strip body, the fish captures the attention of most beginner aquarist during its young age. What most people don’t understand is that the Alligator Gar grows up to 10 ft in length and can only be kept by community aquariums.

The Alligator Gar has a combination of two colors, which include brown and olive colors that allow the fish to hide in dark or dirty water. Their scales are interlocked to make diamond-like shapes. Although they can be 5-15cm when young, the Alligator Gar could grow to a weight of 200 pounds in its adult life stage.

This kind of fish cannot be recommended to a beginner because it requires large and deep aquarium tanks which might prove to be expensive. Alligator Gar also requires lots of food to keep up their size, health, and physical activity.

15. Peacock Bass


Peacock Bass (source)

When it comes to Peacock Bass, you can expect a variety of colors depending on the subspecies, but most are known to have black spots and a yellowish halo on their fins. Sometimes the spots on their body disappear as the fish grows older through its life stages. Their maximum growth length is approximately 24 inches and can weigh up to 15 pounds. A beginner should avoid anything to do with this fish due to its large size, demanding appetite, and also requires a high-quality water environment.

For a complete beginner, it might be challenging to handle the Peacock Bass as they are aggressive, territorial, and fierce predators to small fish in the tank. Specialized experience and a large aquarium are needed to handle and care for the Peacock Bass, and as such, it should be avoided by newbie aquarists.

16. Vampire Tetra


Vampire Tetra

The Vampire Tetra is a remarkable species of fish which can reach the length of 117 cm and just over 39 pounds in its adult life stage. Its body color is silver with transparent fins which are sometimes white or spotted. The fish has a smooth and elongated body and a fan-shaped caudal fin. Its upturned mouth has two fangs and needle-sharp teeth and is an indication that the fish is carnivorous.

These kinds of fish are difficult to keep for newbie because if kept under stressful conditions, they generally have a short lifespan. The level of care required for the Vampire Tetra is delicate and is only meant for advanced experience aquarists. We recommend avoiding this fish because of its high demand for care and maintenance.

17. Piranha


Piranha (CC BY-SA 4.0 source)

The Piranhas are generally medium sized fish, and they grow up to 30 cm in length depending on the level of quality given. The one reason beginners should avoid keeping the Piranha is that it could be illegal in some areas. One should research the legal status of this type of fish in their area.

Another reason to avoid the Piranha is that it requires high-level maintenance and care which it can only receive from an experienced aquarist. A healthy and stress-free Piranha requires space, oxygen, warm water, hiding space, and cleanliness which a beginner might be unable to provide.

18. Northern Pike


Northern Pike (source)

Northern Pike is a species of fish that is relatively large up to 40-55 cm in length. The fish resembles a pike weapon because of its long head, pointy nose, and spiked like fins. The fish has a bar like stripes and spots all over its body, and sometimes the fins are reddish. It is quite a beauty, and beginners might think of adding it to their aquarium.

The Northern Pike is not for beginners’ type of fish as it is an ambush predator and can feed on smaller fish in the tank. The fish might seem expensive to keep based on statistics. It is known that the Northern Pike can swim 8-10 mile per hour, which means it is highly active. Beginners have to invest in building a large and deep tank to afford to keep the Northern Pike.

19. Wolf Fish


Wolf Fish (CC BY-SA 4.0 source)

Based on its name, the Wolf Fish could prove to be hard to keep even for medium experienced aquarists. They are one of the most aggressive fish and can grow up to 39 inches, which are pretty big for a home aquarium. These types of fish are best suited for community aquariums because of their size, feeding behaviors, and they can breed up to 6000 eggs during the mating season.

A beginner might not have the capacity to store and care for the fingerlings that might manifest after the breeding season. Another thing is that beginners might not be able to handle the Wolf Fish in the tank because it can attack and feed on smaller fish. It thus needs experienced aquarists to match it well with its appropriate tank mates.

20. Freshwater Stingray


Freshwater Stingray (CC BY-SA 4.0 source)

Freshwater Stingrays are closely related to sharks skates, guitarfish, and sawfish, but they are commonly known for their poisonous barb. They have cartilage skeleton rather than actual bones with a black spot on a brown background body. That said Freshwater Stingray requires scrupulous care and maintenance, which can only be accomplished in a large aquarium.

Unfortunately, for a beginner to keep Freshwater Stingray, it must feel very dull, mainly because this fish has to be kept alone. Freshwater Stingrays are carnivorous and may eat other fish in a tank. For the beginners avoid this fish because it is expensive to maintain and its venom sting might prove to cause life-threatening allergies if handled carelessly.


Keeping a single or collection of fish in the aquarium is a fun thing to do mainly for complete beginners. For some of the reasons mentioned above, it is crucial to analyze the personality, size, feeding habits, and general behavior of fish before trying to keep them in your tank.

Some fish species are not recommendable to beginners because they are too large, they are aggressive, difficult to handle, require special attention, and some are expensive to buy and maintain. No matter your enthusiasm to start keeping fish, it is essential to do some research for its suitability in your aquarium.

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