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Bucktooth Tetra: Pictures, Size, Care & Tank Setup

Sarah Psaradelis

By Sarah Psaradelis

bucktooth tetra in aquarium

One of the most aggressive species of tetra is the Bucktooth Tetra (Exodon paradoxus). This species of tetra is known for being highly aggressive and territorial, making them a menace in communal aquariums. It is unclear where the Bucktooth Tetra got their name from since they do not have any visible teeth.

Size: Up to 5 inches long
Lifespan: 8–10 years
Similar Breeds: Blood Tetra, Diamond Tetra, Ember Tetra
Suitable for: Experienced fish keepers
Temperament: Aggressive, territorial, social

The Bucktooth Tetra is both a freshwater and tropical fish that is well-known for its highly territorial nature in aquariums. They are far from peaceful, yet they are social fish that need to be kept in large groups.

Despite their aggressive temperament, Bucktooth Tetras make fascinating aquarium fish with specific housing and care requirements. Beginner fish keepers might be overwhelmed with the Bucktooth Tetras’ compatibility and behavior in aquariums. This makes them a better choice for experienced fish keepers who are knowledgeable about aggressive fish species and their care.

If you are ready to commit to caring for Bucktooth Tetras in your aquarium, this article will discuss what their care entails.

Bucktooth Tetra Characteristics

Ease of Care

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How Much Do Bucktooth Tetras Cost?

Bucktooth Tetras might not be very popular fish, but they are not considered rare. They originate from the tropical waters of South America, specifically the Amazon and Orinoco river basins. They form large shoals and display predatory behavior that makes them difficult to raise in community aquariums. The Bucktooth Tetra has been in the aquarium trade since the early 1930s and can be found in large populations in both captivity and the wild. Although Bucktooth Tetras aren’t in popular demand in pet stores, this is the easiest way to purchase them.

If your local pet store happens to stock Bucktooth Tetra, you can expect to pay around $5 to $18 for one of them. However, you will need to buy more than one Bucktooth Tetra since they are shoaling fish. This means that you might be spending a total of $30 to $90 for a group of six Bucktooth Tetras.

bucktooth tetra fish
Image Credit: Pavaphon Supanantananont, Shutterstock

Sociability of the Bucktooth Tetra

Do These Fish Make Good Pets?

Bucktooth Tetras can make good pets for experienced fish keepers. These aggressive and territorial fish are a poor choice for beginners and keeping them alive can be challenging without prior experience.

This is primarily because Bucktooth Tetras require very large tanks that have specific tankmates, water quality, and tank setups. They should not be housed in bowls or small tanks, as this is highly stressful for them and can cause them to die prematurely. They are naturally tropical fish, so temperature is very important for their overall health and longevity.

Furthermore, Bucktooth Tetras do not cohabit well with other species of fish and may need a spacious tank all to themselves. You won’t be able to keep them with other fish or raise them in a community tank without careful consideration and backup housing if they start acting aggressively towards the other fish.

The Bucktooth Tetra can be hardy and adaptable, but good water quality is essential for them. Their tank must be fully cycled a couple of weeks before any of them are added. They do not tolerate traces of ammonia and nitrite in their water, which can cause them to die relatively quickly.

Does This Fish Make a Good Tank Mate?

In comparison to many other species of tetras which are social and peaceful, the Bucktooth Tetra is a poor tankmate for other fish. The best tankmate for a Bucktooth Tetra is their own species. You should not house Bucktooth Tetras alone or in pairs since this could make them feel unsafe and stressed. They form shoals in the wild and thrive in groups of six or more. Keep in mind that the more Bucktooth Tetras you keep, the larger their tank needs to be.

Bucktooth Tetras are known to harass other fish by chasing them and nipping at their fins. A group of Bucktooth Tetras can be quite destructive to other peaceful fish, even other tetras. They are also known to eat small fish, so even Neon Tetras and Rasboras are not compatible tank mates for them. Bucktooth Tetras don’t only pick on fish their own size and will try to bully larger fish like African Cichlids as well.

It is much better to keep Bucktooth Tetras in a species-specific tank. This allows you to enjoy the species in their environment and observe their predatory behavior and social temperament without the distraction of other fish.

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Care Guide & Tank Set Up

Bucktooth Tetras need very large tanks to support their adult size and shoals. A minimum tank size of 55 gallons is recommended for a group of 6 to 12 Bucktooth Tetras. They should be kept in standard rectangular tanks rather than tall ones since they require more horizontal swimming space.

Water Quality, pH, & Temperature

Bucktooth Tetras are tropical fish, so their tank needs to be equipped with a heater. Their water temperature should be stable with few fluctuations, although a gradual drop of one to two degrees isn’t much of a concern. They prefer soft and slightly acidic waters which they experience in their wild habitat.

Temperature: 72°–82° Fahrenheit (22°–28° Celsius)
pH Range: 5–7.5
Water Hardness: 70–350 ppm
Ammonia: 0 ppm
Nitrite: 0 ppm
Nitrate: Below 15 ppm

Care tip: Your Bucktooth Tetras water parameters can only be determined by a water testing kit. You cannot visibly see the ammonia, nitrite, or nitrate levels. An aquarium water testing kit will be able to give you an accurate reading of the water parameters.

holding PH tests in front of freshwater aquarium
Image Credit: M-Production, Shutterstock


Most aquarium substrates like gravel, sand, quartz, and pebbles can be used in Bucktooth Tetra aquariums. However, they seem to prefer sandy substrates. Their wild habitat consists of sandy and muddy substrates with dense vegetation. Replicating their wild habitat in captivity allows these fish to feel more at ease and display their natural behaviors. Besides, sand is an excellent growth medium for many aquarium plants too.


Bucktooth Tetras thrive in heavily planted tank setups. They enjoy having live plants in their aquarium, and dense vegetation makes them feel secure in their environment. Many different aquatic plants are compatible with Bucktooth Tetras as they are not known to eat plants. However, you want to ensure that any aquatic plants you choose can grow in the same water conditions as your Bucktooth Tetras.

You may need to use fertilizers and CO2 systems to enhance the plants’ growth if you want to create the heavily planted setup the Bucktooth Tetra prefers.

Best Plants for Bucktooth Tetras:

  • Java fern
  • Bacopa
  • Hornwort
  • Anubia
  • Ludwigia
  • Anacharis
  • Brazilian pennywort
  • Java moss


Bucktooth Tetras require low to moderate lighting over their tank rather than very bright lighting. Aquarium lighting is necessary to create a day and night cycle for these tetras and for live plant growth. Bucktooth Tetras need to have a light on their tank for around 6 to 12 hours at a time. This lighting should be turned off at night because Bucktooth Tetras rest in total darkness. It is not necessary to use aquarium night lights that are used to mimic natural moonlight.

Bucktooth Tetras do not need natural sunlight from a window, which can even be dangerous for them. Although they are tropical fish, harsh sunlight can cause dangerous temperature fluctuations.


Running a filter on your Bucktooth Tetra’s tank is not only necessary but incredibly important for their survival. A filter will help to aerate the water and keep it moving, fresh, and clean for your Bucktooth Tetras. The filter will host beneficial bacteria that help keep the ammonia levels under control by offering biological filtration.

The mechanical filtration part will remove floating debris that would contribute to poor water quality. Some filters also offer chemical filtration where filter media (such as activated carbon) can be used to remove impurities from the water. The filter’s current shouldn’t be too strong, and a low to moderate flow is recommended.

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Things to Know When Owning a Bucktooth Tetra:

Food & Diet Requirements

The Bucktooth Tetra is a carnivorous and predatory fish that needs plenty of protein in their diet. In the wild, Bucktooth Tetras have been observed to eat the scales off of other fish. They prey on small fish, insects, fish fry, and larvae. They do not eat much vegetation in the wild and prefer to stick to an animal-based diet. A Bucktooth’s main source of nutrients should be from a quality flake or pelleted food. This food should be formulated for carnivorous fish and contain few plant-based ingredients.

Their diet should be supplemented with plenty of live or freeze-dried foods like bloodworms, brine shrimp, and finely chopped mussels or prawns. Bucktooth Tetras will readily accept many live insects like crickets and earthworms, but only if they are from pet stores. Wild insects may carry diseases and parasites that are dangerous for Bucktooth Tetras.

Size & Growth Rate

Bucktooth Tetras seem to grow larger in the wild than they do in captivity. Wild Bucktooth Tetras generally have an average size of 5 to 6 inches in length, whereas captive Bucktooth Tetras only grow between 3 to 5 inches in size.

These fish do most of their growth within the first year of their life. They are usually fully grown within a couple of months and reach maturity at around 4 to 6 inches.


The Bucktooth Tetra is the sole member of the Exodon genus and can only be found in one variety. They have a fascinating appearance, which is one of the reasons fish keepers are drawn to this species. Bucktooth Tetras have an elongated body, with females being slightly larger than males.

They have a colorful metallic silver body with two distinctive dark circles along their bodies. One circle is usually at the base of the tail, while the other one is located between the head and dorsal fin. An orange or yellowish streak runs across the top part of their body and is most visible under aquarium lighting.

Their fins are often orange or red, except for their caudal fin which is either yellow or light orange.

Lifespan and Health Conditions

The Bucktooth Tetra has a fairly long lifespan in comparison to some other tetra species. A well-cared-for Bucktooth Tetras can live for up to 10 years, although 8 years is average for the species.

Aside from proper care and aquarium maintenance, the Bucktooth Tetra’s health can affect their longevity. Although they are relatively hardy fish, they are still susceptible to certain health conditions. These health conditions could be caused by parasites, viruses, and even poor water quality.

Minor Conditions
  • Minor abrasions leading to a few missing scales
Serious Conditions
  • Black spot disease
  • Ich/white spot disease
  • Velvet
  • Fin rot
  • Dropsy
  • Columnaris worms
  • Ammonia poisoning
  • Fungal infections

aquarium plant dividerMale vs Female

The male and female Bucktooth Tetra are quite similar, and it can be difficult to differentiate between both sexes. However, they are a sexually dimorphic species with slight differences in their appearance. Male Bucktooth Tetras can be distinguished by their slimmer appearance and longer and pointier fins. Female Bucktooth Tetras have a rounder stomach, which is most noticeable during spawning season.

There isn’t much of a difference between their temperaments, however, males might be more aggressive during spawning.

3 Little-Known Facts About Bucktooth Tetra

1. Despite their name, the Bucktooth Tetra does not have any big, visible teeth.

2. Bucktooth Tetras have tiny, unique rows of teeth that are designed to rip and eat scales from either live or dead fish. They are lepidophagous or scale-feeding fish.

3. The Bucktooth Tetra is the only member of the Exodon genus.

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Final Thoughts

If you decide on the Bucktooth Tetra as a pet, it’s good to have experience caring for aggressive fish, and knowledge of their water and housing requirements. They are predatory fish that do not do well in community aquariums but thrive when kept in groups of six or more of their species. Bucktooth Tetras are active fish that need a spacious tank and plenty of live foods in their diet for protein.

When Bucktooth Tetras are properly maintained in an aquarium and all their care needs are being met, they can live for up to a decade. This makes them a long-lived and colorful species of tetra that is on the more aggressive side.

Featured Image Credit: Michal Sloviak, Shutterstock

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