Bucktooth Tetra 101: Care, Diet, Habitat, Look & More | 2023

By: Martin McAdam
Updated: April 9, 2023

Bucktooth Tetra is one of the most popular tetras in the aquarium hobby. They are hardy, inexpensive, and come in various color morphs, making them an attractive addition to any community tank.

Ecologically speaking, they inhabit some of the blackwater, flooded forest tributaries throughout South America found in the Amazon, Orinoco, and Paraguay River basins.

They are found in blackwater rivers/lagoons with high tannin content, making the water quite acidic, and whitewater rivers with little to no current, obvious water.

If you're considering adding a Bucktooth Tetra to your aquarium, read on to learn about their care, habitat, lifespan, size & diet!

Bucktooth Tetra: Species Summary

Scientific Name:Exodon paradoxus
Origin:Amazon Basin and Guyana
Size:Up to 4.7 inches (12cm)
Lifespan:Up to 10 years
Temperature range:70°-82° F
pH range:5.5 - 7.5
Tank size:55 - Gallons
Water Hardness:2-10 dGH
Compatibility:With Aggressive or Larger Fish
Water Type:Freshwater
Nature:Aggressive with small fish, invertebrates & Plants
Care Level:Difficult
Color Form:Silver body with golden stripes and two black spots

In the aquarium, they do well on a flake, frozen, freeze-dried, and live foods diet.

Bucktooth Tetras are a very hardy and adaptable species that can be kept in nearly any water type. They generally school well with other similarly sized aggressive fish but may become stressed if kept as a single specimen.

They will usually school together at night and rest on the bottom of the tank or near dense plant growth, depending on whether or not they originate from blackwater or whitewater habitats, respectively.

Bucktooth Tetras can become very shy if not provided with hiding places, such as dense plant growth, especially during the daytime when they are more active.

To add to the beauty of a planted aquarium, they will school together in the open and provide a stunning sight against the greenery with their bright contrasting colors.

Bucktooth Tetra: Origin

Bucktooth Tetras are initially from the blackwater-flooded forests found in South America. Here they live in dense plant growth among roots and leaf litter, which provides them with their natural habitat.

Blackwater is characterized by having very acidic water with negligible hardness due to organic acids leaching into the water column that originate from decaying leaves, trees, and other plant matter.

These flooded forests have a tiny current due to the lack of dissolved oxygen. The water has a very dark, tea-like coloration from which this tetra's scientific name derives (metynnis means "minnow," and loretoensis refers to its place of origin, Loreto).

Also Read: Sailfin Pleco Care 101: Diet, Size, & More | 2023 Updated |

Bucktooth Tetra: Phenotype and genetic traits

As with all captive-bred fish, there are several different color morphs of Bucktooth Tetras that you can purchase at your local pet store. Some common ones include the person with albinism, gold variety (metynnis lucius), electric blue, and marble variety (metynnis hypsauchen). Many more can be purchased, but these are perhaps the most attractive.

All these color variations originate from different populations in South America, where they have either been naturally selected due to their survival advantage or are selectively bred by man.

When kept in captivity, it can be challenging to determine where their genetic ancestry begins and ends. Except for the albino morph, they are sexually monomorphic, meaning there is no differentiation between males and females when viewed externally.

Genetic diversity among Bucktooth Tetras is high, making them a very resilient species in captivity, particularly regarding water parameter tolerances and disease resistance.

This trait is essential in a captive population whose natural habitat has been severely reduced by outside forces such as deforestation and the pet trade.

Also Read: Blood Parrot Cichlid Best Care Guide, Lifespan, Size & All | 2023

Bucktooth Tetra: Appearance

Red-eyed black tetra is one of the most popular aquarium species due to its ease of maintenance and, as juveniles, their striking black coloration.

The body is brownish-olive with a red ring around the pupil of the eye and a second, smaller ring at the front plate of the eyeball. There are vertical, thin stripes on the body. The belly is white, and they have an adipose fin (a small fleshy lobe behind their dorsal fin).

Bucktooth Tetra Appearance

Males are more robust than females, with a more giant head, thicker caudal peduncle, and an apparent red stripe on either side of the anal fin, continuing with two stripes to the tail.

Females have a more gentle sloped forehead and thinner caudal peduncle, and their anal fin is less intensely colored.

Mature adults are typically black with narrow whitish bands on the flanks, but some color variants can be completely black (with no bands), silver (a metallic sheen), or gray (which may be compared to a "dirty" version of silver).

Adult females are usually more black with a greenish sheen, while male colors are more intense. Their belly is lighter than their back or vice versa.

Juveniles typically have a dark head and a narrow stripe running from the snout, through the eye, and to the tail. The rest of their body is very dark brown.

The common name of "Bucktooth Tetra" comes from the small teeth in their mouth. However, it is essential to note that they are not venomous or harmful to humans.

The upper stripe will disappear as they mature, leaving them with a back that varies from pale cream to yellowish or olive green with darker mottling along the lateral line. The white belly usually has no patterning.

Bucktooth Tetras are generally aggressive fish that will do well in a community tank or a community tank with other similarly sized, non-aggressive species.

Bucktooth Tetra: Size & Growth Rate

The Bucktooth Tetra will reach a maximum size of 5 inches in the aquarium.

Bucktooth Tetra: Lifespan

Due to the wide range of their natural habitat and water parameters, it is difficult to determine a specific lifespan. They have been known to live in the aquarium for up to 10 years.

How Much Do They Cost?

Bucktooth Tetras should cost you about $2.50 to $3 per fish, but they should ideally be bought from a pet store rather than Craigslist or other sources. They may appear gaudy but are usually relatively cheap and make good tankmates for smaller species, such as neon tetra and cardinal tetra.

Bucktooth Tetra: Behavior

They can be kept as single species schools, but due to their active nature during the day, Bucktooth Tetra will school better when kept with groups of at least 6 of their species for the best effect.

Bucktooth Tetra Behavior

At night they will sleep in a group huddled up to one another, usually on the bottom of the tank or near dense plant growth, depending on whether or not they originate from blackwater or whitewater habitats, respectively.

If kept singly, they may become stressed, spend most of their daylight hours hiding, and only come out at night to feed.

Bucktooth Tetra: Food & Diet

Bucktooth Tetras are omnivorous and will eat all kinds of foods that you offer them. Their natural food in the wild consists of insects, worms, crustaceans, algae, plant matter (detritus), small fish larvae, and various larger organisms found in their habitat (they are usually born in standing water).

These larger organisms (frogs, mice, insects) should only be offered as a treat since they are nutritionally poor and will probably not be eaten.

It would be best to keep their diet primarily plant-based by adding live food such as brine shrimp and bloodworms or frozen bloodworms (defrosted).

Bucktooth Tetras will eat various foods, including flake food, frozen brine shrimp or bloodworms, and tubifex worms (live or frozen), and they will also eat small insects that fall into their tank.

As with most fish, it is beneficial to supplement their diet with vegetables such as zucchini slices, romaine lettuce, spinach leaves, etc.

Bucktooth Tetra: Temperament

Bucktooth Tetras are a peaceful, active species that will make an excellent addition to most community tanks. They can be shy in a new tank but may become more friendly the longer they are there.

Like all fish in this family, they have small teeth in their mouths and can cause a fair bit of damage when they decide to defend themselves from something they perceive as threatening.

As with any fish, it is best not to keep them with minor or less aggressive tank mates that may be considered prey by the tetra.

How Difficult Are They To Breed?

Breeding these fish is pretty straightforward, although you must remember that the fry may not survive if the parents do not adequately care for them. In most cases, you should add breeding traps to your tank when you want to breed them.

This can be a small mesh bag that floats just below the water's surface, making it easy for the parents to deposit eggs while fertilizing it.

What Is The Best Way To Prepare Them For Breeding?

Bucktooth Tetras can be bred without too much difficulty. The first step would be to condition the fish by feeding them live or frozen brine shrimps, bloodworms, or tubifex worms. Once they are in breeding condition, the next step would be to select suitable mates.

Males will often become more territorial during the breeding process and may fight with each other. Be sure to keep a ratio of three females for every two males (assuming you have a large enough tank - at least 55 gallons). Keeping the females in a separate tank from the prospective males would also be a good idea.

The reason for this is that there is some evidence that the presence of females will deter the males from acting aggressively toward each other.

Next, you will need to provide an ideal environment for breeding. This can be achieved by providing a heavily planted breeding tank with dim lighting and dark substrate.

Livebearing fish such as swordtails, mollies, and platys often spawn together in the planted aquarium. The more live plants there are, the more likely they will spawn without being frightened away from their eggs by other fish species that would disturb them.

As a result, the water should be soft and acidic with a pH between 4.0-6.5 and a dGH range between 2-10 to mimic their naturally occurring environment for maximum breeding success.

Bucktooth Tetras will usually lay eggs on broad-leafed plants such as Amazon swords, but they have also been known to spawn on broad-leaved floating plants such as water lettuce.

It is pretty standard for them to scatter their eggs in different areas of the tank, and there may even be some debate over whether they do this while still in the fry stage or only after they become free swimming.

The eggs will usually hatch within 48 hours, depending on the water temperature (warmer temperatures yield faster hatching).

Once hatched, the fry will be tiny and should be fed infusoria or newly hatched brine shrimp until they are large enough to eat newly hatched baby brine shrimp, microworms, or commercially prepared fry food.

It is also beneficial to place the breeding tank under the moonlight or leave the fish in the dark for 12 hours daily to simulate their natural lunar cycle, which can help speed up spawning and increase fertility rates.

How difficult are they to spawn?

Bucktooth Tetras are not particularly difficult to spawn. Like most fish, the first step is getting them in breeding conditions (feeding live or frozen brine shrimp, bloodworms, and tubifex worms).

The next step would be to select suitable pairs and provide an ideal environment for breeding (a heavily planted tank with very dim lighting and dark substrate).

Once they are in breeding condition, you must keep the fish together for a few days, and they should begin spawning.


Bucktooth Tetras are best kept in groups (preferably 10 or more), although they can be kept singularly if necessary. They will not attend school but seem to prefer being in large shoals of their species.

They should be kept in a roomy tank with good filtration and at least 10 gallons per fish. While they can be kept in almost any community tank, they do best in heavily planted tanks with lots of live plants and hiding places.

It is also advisable to keep them in a species tank if you plan to breed them.

Bucktooth Tetra: What Are Their Mating Patterns

Like most of this family, Bucktooth Tetras breed through egg scattering, where the female scatters eggs and the male fertilizes them simultaneously, causing them to drift throughout the tank.

This form of egg scattering can be dangerous if not done correctly since it may result in eggs being eaten by other fish or dying off for lack of filtration or poor water quality.

To prevent this from happening, you should try to keep water changes regular while they are breeding.

Bucktooth Tetra: Care

Bucktooth Tetras are generally very aggressive fish that will do well in a community tank or a community tank with other similarly sized, aggressive fish. They are very hardy fish that will adapt to most water parameters.

Bucktooth Tetra Care

Bucktooth Tetras should be kept in groups of at least 6 or more of their species for the best effect. They are non-aggressive towards their kind and will school together during the day.

At night they will sleep in a group huddled up to one another, usually on the bottom of the tank or near dense plant growth, depending on whether or not they originate from blackwater or whitewater habitats, respectively.

Will They Get Along With Other Species?

Bucktooth Tetras can be kept in a community tank and a "show" type of planted aquarium. In either case, they will thrive if the water is warm, soft, and acidic, with a pH between 4.0 to 6.5 and a Water hardness range between 2 to 10.

In the community tank, they will do very well with other similarly sized, non-aggressive fish such as hatchet fish, pencil fish, head and tailpipes, kuhli loaches, fantails, etc.

In the planted aquarium, they will do well with catfish such as Corydoras, hatchet fish, pencil fish, head and tailpipes, and small kuhli loaches.

Tank Conditions

Bucktooth Tetras can be kept in a community tank and a "show" type of planted aquarium. Either way, they will thrive if the water is warm, soft, and acidic.

Tank Size

Bucktooth Tetras are safest when kept in a group of 6 or more of their species. They can be kept singly, but they can become stressed and shy away from activity altogether, only coming out at night to feed.

A 5-gallon tank will suffice for a single individual or a small group. A 12-gallon tank can house a group of 5 or less, with 15 gallons and up being the minimum suggested size when keeping larger groups.

Tank Region

Bucktooth Tetras prefer a densely planted aquarium with plenty of hiding places in the form of driftwood or rock structures and dense plant growth.

They will school together in the afternoon when they become active, but at night you will see them sleep near one another on the bottom of the tank or near the dense plant growth, depending on where they originate.

Water Conditions

Bucktooth Tetras are sensitive to deteriorating water conditions. Therefore, regular small partial water changes should be performed weekly.

They can tolerate a relatively wide range of dGH and pH, but nitrate levels should remain below 40 ppm for wild-caught specimens. For the best coloration, they prefer soft water with a dGH range between 2 to 10 and a pH between 4.0 to 6.5 for wild-caught fish to breed.

Does Bucktooth Tetra Have Any Special Requirements

Bucktooth Tetras are fish that will live well in most community tanks if you provide filtration, a good diet, and regular water changes. They prefer heavily planted tanks with lots of hiding places and a soft substrate or gravel to sift through to find food.

They may breed in smaller tanks (20 gallons or less), but it is better to keep them in at least a 30-gallon, heavily planted tank with the addition of some river stones or other decoration for breeding purposes.

These fish are also susceptible to water quality and pH changes, so it is best to keep their environment stable while breeding.

How Hardy Are Bucktooth Tetras

Bucktooth Tetras can survive in various conditions and often do well when their breeders keep the water quality high and stable. They may initially be fussy about water parameters but usually acclimate well if given time.

They can tolerate a pH of up to 8.5, although anything above 7.5 is not recommended for keeping this species long-term. They can survive in temperatures as low as 7°C (45°F) but should ideally be kept between 23° to 26°C (73°F - 79°F).

If they are stressed (which can happen if their tank mates are too aggressive or their water is of poor quality), they may not eat regularly and can develop a myriad of illnesses.

Moving them into a more stable environment with filtered water is essential if this happens.

What Else Should I Know About Them?

The common name of "Bucktooth Tetra" comes from the small teeth in their mouth. However, it is essential to note that they are not venomous or harmful to humans. They are often found in the Amazon River, which may be hard to spot due to their small size and dark coloration.

As with all fish, keeping them in an environment with clean water and a strong filter is essential. They will appreciate being kept with other peaceful fish, although the larger the tank, the better, as they tend to be more active when kept in larger groups.

If you notice any of your fish acting differently or seeing signs of sickness, please check your water parameters and change your tank as needed to prevent illness.


These fish are fairly adaptable in lighting but prefer dim lighting or even floating plants to provide shade in their tank. Lighting should be bright but not harsh, and the tank should be well-covered to prevent jumps despite its small size.

Placement And driftwood

Since these fish prefer a soft substrate and lots of plants, it's important to remember this when selecting a location for their tank.

Driftwood can help mimic the environment they come from while providing extra shade. Using gravel or other sharp substrates, consider adding river stones or decor to create hiding places.

Water Changes

These fish are susceptible to water conditions and pH, so it's important to provide them with stable water parameters before expecting them to breed.

Frequent water changes are best for these fish to maintain a healthy environment without too much stress on their body. This will also help eliminate the buildup of harmful substances in the water before they can affect their health.


When it comes to heaters, these fish prefer their water temperatures within a range of 23°-26°C (73°F - 79°F). Keeping the water temperature stable is especially important during the breeding period.


These fish are sensitive to water conditions, so they must have a strong filter in their tank. A canister filter or even multiple power filters may be needed for this species if you notice they are being stressed by the filter's current in their tank.

Gravel And Substrate

These fish are not picky regarding the substrate; provided there is a layer at least one inch deep. If you plan on adding a deeper substrate, driftwood, or another decor for your Bucktooth Tetra, be sure that it does not have sharp edges which could damage its body.

Most breeders prefer soft and fine gravel or sand that does not get sucked into the filter and is easy for the fish to sift through.

What About Aquascaping?

Bucktooth Tetras are adaptable fish but do best in densely planted aquariums with many hiding spots. Driftwood, rocks, and even large pieces of PVC make good decorations for the tank.

We recommend using anubias (yup), water sprite (hygrophila), or java fern (narrow leaf), as these plants stay low to the bottom of the tank and provide a good hiding place for your tetras.

Floating plants like Amazon frogbit or water lettuce can also help shade the aquarium from lights.

What Equipment do I need?

Bucktooth Tetras should be kept in a tank of at least 20 gallons but no more than 30. They are best suited for tanks with low-moderate water flow, although they may need extra aeration if they do not have large amounts of surface disturbance.

They should be kept in schools of 6 or more fish and need plenty of hiding spots and decorations. We recommend using a well-rated filter for a tank of this size, such as an AquaClear 20 or Eheim 2217.

Bucktooth Tetra: Common possible diseases

  • Fish tuberculosis: Tuberculosis can attack various fish and is contagious.
  • Dropsy: Dropsy is brought on by a bacterial infection that causes scales to stick out.
  • Hole in the head: it is not known why this disease attacks fish, but it can be treated with antibiotics or, in some cases, by performing a partial water change.
  • Ich: This parasitic disease is common among fish and can be treated with salt.
  • Lice: Lice are caused by a parasite that lives on the body of fish, most commonly found in wild-caught fish.
  • Velvet: This iparasiteattaches itself to the skin or gills of fish, but it is easily treated bsing a quarantine tank and copper sulfate. More information on these fish can be found here:
  • Bucktooth Tetra Symptoms: Fish stops eating, swims lethargically, fins clamped to side, stomach swells, may have red streaks near tailfin, fish starts to lose color, scales turn white.

Bucktooth Tetra: Medicines and Treatments

Aquarium salt can help with many treatments, and we recommend using it when the fish is sick. It also helps prevent illness in healthy fish.

Melafix is a natural treatment that can treat external bacterial infections such as fin rot and mouth fungus, but only use it if your Tetras cannot breathe!

Kordon's NovAqua+ is a treatment that helps cure diseases such as fish tuberculosis and can help prevent many other types of illness.

Are They Dangerous?

Bucktooth Tetras are not venomous to humans, but they may nip at the fins of other fish.

Are Bucktooth Tetras Suitable For Beginners?

Bucktooth Tetras are very hardy fish and are great for beginners, although you must provide them with proper water conditions regardless of their experience.

While they are not as fragile as guppies, they require a different approach to water conditions than other types of fish.

How many Bucktooth Tetra should I add?

Bucktooth Tetras are best kept in schools of 6 or more, so if you plan to add them to a community tank, be sure it already has at least 6 or more fish.

They prefer dim lighting and go by color rather than by species. If they do not like the color of particular fish, they may nip at their fins and harass them until the fish leaves.

How Do I Know If My Bucktooth Tetra Is Stressed?

If your tetras are acting sick, look for these common signs of stress:

  • Loss of appetite: This is the number one sign that your tetras are stressed. They will get sick or die if they do not eat, especially if you have sensitive fish like tetras. The best way to combat this is by stocking your aquarium with many different foods and feeding your Tetras a variety.
  • Lethargy: They are probably stressed out if they are not swimming around, playing with the other fish in the tank, or eating.
  • Loss of coloration/or white scales: This may indicate illness or damage to the fish.
  • Visible fungus: This is another sign that your fish are sick, and you should check the water condition and quality often to ensure there isn't an underlying cause such as disease, parasites, or neglect.
  • Clamped fins: This is usually a sign of aggression or illness, not too much, unlike lethargy.
  • White spots: These could be signs of damage caused by other fish in the tank, so it's essential to keep an eye on your whole tank.
  • Listless behavior: The fish seems to have given up swimming around and just staying in one place.
  • Swim bladder problems: These are caused by high amounts of ammonia and nitrites in the tank.

If you notice any of these symptoms, it is best to immediately check your water quality and perform a partial water change with dechlorinated or spring water. If you need help, read our how-to article on setting up an aquarium for dummies.


Bucktooth Tetra can be an excellent addition to your community tank, but it is essential to remember that some fish out there eat smaller ones. You should do some research and know what you want before you go and buy anything. This article gives you a general idea about the Bucktooth Tetra. Knowing what kind of fish you want is important before you buy it.


AquaMarinePower.com does not intend to provide veterinary advice. We go to great lengths to help users better understand their aquatic friends. However, the content on this blog is not a substitute for veterinary guidance. For more information, please read our disclaimer.

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