Bucktooth Tetra 101: Care, Feeding, Aggression, & More

Bucktooth tetras are a unique and active freshwater fish that definitely stand out. These are not your typical tetra!

But their high level of aggression is something you need to be aware of before you even consider owning some for yourself. This species can be downright nasty!

This guide will teach you how to handle their feisty nature, and get prepared for all other aspects of bucktooth tetra care.

Species Summary

While the bucktooth tetra is part of the tetra family, it’s nothing like the peaceful community fish most familiar with! Scientifically known as Exodon paradoxus, this freshwater fish is predatory and wildly aggressive.

Best for seasoned aquarists, the bucktooth tetra can be violent towards any other fish in the vicinity. They are one of several scale-eating species from the Amazon River Basin. Groups will swarm fish and rip their scales off bit by bit!

Bucktooth tetras are naturally found throughout Brazil and Guyana. While not as popular as their peaceful cousins, this species is still readily available in the aquarium trade.

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Revered for their beauty and ferocious nature, they are considered a must-have for many aquarists!


The bucktooth tetra is similar in appearance to other types of tetra species. They’re small, torpedo-shaped, and quite colorful!

The base color is metallic silver. However, the silver is adorned with hints of yellow, green, and red. Two large spots accent the body as well. One is in the middle of the body and the other is on the base of the tail.

Bucktooth tetra swimming in a freshwater aquarium

The fins are transparent with a hint of yellow. Red and orange splotches cover the dorsal, pectoral, and anal fins. Meanwhile, flecks of brighter yellow add a pop of color on the tail!

Despite their creative name, these freshwater fish do not have protruding teeth. However, their teeth are still quite unique. To help with the fish’s scale-eating habits, the teeth are pointed and quite sharp. They can easily get underneath tough scales to rip them out!

The teeth and lips are positioned to be outward-facing, which further enables them to do damage and bite other fish. As menacing as this sounds, it’s actually quite hard to see their teeth unless you look carefully up close.


The lifespan of a healthy bucktooth tetra can reach upwards of 10 years. That’s pretty much on par with other tetra species.

Like any other fish, bucktooth tetras need a well-maintained environment and an appropriate diet to reach their maximum life expectancy. Without quality care, these fish could suffer from disease and early death.

Average Size

The average size of a bucktooth tetra is around four to five inches when kept in captivity. However, they can reach up to six inches in length in the wild!

Author Note: Many aquarists have tried their best to get bucktooth tetras to reach the six inch mark in captivity, but it rarely works out. Even with massive tanks and elaborate feeding strategies, this freshwater species always seems to remain smaller when kept in an aquarium.

Bucktooth Tetra Care

Bucktooth tetra care is usually best reserved for aquarists with a bit of experience. These are truly extraordinary fish with some very distinct behaviors and needs!

To be honest, they can be a bit of a challenge regardless of your experience levels. But with a bit of know-how and dedication, caring for these fish should be manageable.

Here are the main care guidelines to follow!

Tank Size

First things first, you need a spacious tank if you want to keep these fish! For a group of 12 bucktooth tetras, we recommend using a tank that can hold no less than 55 gallons.

Author Note: Of course, a bigger tank is always better. This is especially true if you want to keep an even larger group.

If you think that’s rather large for a relatively small fish, here’s why it’s important:

Bucktooth tetras are quite active and need ample space to swim around and explore. Furthermore, they are shoaling fish. You must keep a large group together to avoid any infighting and cannibalistic behavior (more on that later).

Water Parameters

Bucktooth tetras aren’t too demanding when it comes to water parameters. They do fine in standard water conditions that suit the many South American tropical fish out there.

In the Amazon River Basin, waters are warm and teeming with life. Thanks to the debris that lines the river bed, waters are usually on the acidic side as well.

  • Water temperature: 72°F to 82°F (roughly 75 degrees in ideal)
  • pH levels: 5.5 to 7.5 (aim for slightly acidic)
  • Water hardness: 0 to 15 KH

Author Note: Make sure to go out and get yourself a reliable aquarium water testing kit to help you monitor these conditions on a consistent basis. This will allow you to make adjustments and changes before any of the parameters slip to a dangerous level.

What To Put In Their Tank

These fish aren’t crazy about using plants as a place to hide. They’re far too aggressive and active for that! However, they still prefer to have some vegetation that they can zip through.

A mix of live plants can do these fish a lot of good. Go for plants like Java fern and Amazon swords. Grass-like plants in the foreground and a few floating plants in the aquarium are good options as well.

But make sure you don’t overcrowd the tank with plants! Keep them around the perimeter to create a natural setup that still allows them to swim. Bucktooth tetras aren’t known to damage plants, so they should thrive in an aquarium with this kind of setup.

For the substrate, use a dark sand material. These freshwater fish like to stick to the middle and top of the water column, but they may venture down there for food. Sand is safe and natural-looking.

Author Note: Additional decor is always a good idea too. You can add some driftwood, caves, and rocks. Like the plants, don’t overdo it! Keep things simple and focus on providing an open swimming space.

Common Potential Diseases

There are no unique health issues to worry about with the bucktooth tetra. However, they can still suffer from all the usual ailments that plague other freshwater species.

These fish can come down with ich, suffer from bacterial infections (like fin rot), or fall prey to parasites all the same.

The good news is that most major health problems are easy to avoid. Bucktooth tetras are quite hardy, but they can react negatively to major temperature or pH fluctuations. A buildup of ammonia and nitrates in the water can do some serious damage too.

Maintain the proper water conditions and make sure that you’re using a powerful filtration system to keep the environment in good shape. Partial water changes every week or two are important as well.

Food & Diet

Bucktooth tetras are carnivores through and through! In the wild, their diet consists of mainly fish scales.

When they eat scales, a group will swarm their prey and attack from all directions! This is actually quite piranha-like in nature.

It might take a second to get used to this unique feeding experience, but it’s not too difficult once you get the hang of it.

Many owners will provide dead or live feeder fish to meet these requirements. You can also offer up some other high-quality protein sources for the sake of variety as well. They will readily accept brine shrimp, bloodworms, earthworms, and other insects.

Author Note: Some fish will even take commercial flakes, but don’t expect them to stay satisfied with flakes or pellets alone. To keep these fish healthy, they need protein-based foods!

Behavior & Temperament

As we mentioned earlier, bucktooth tetras need to stay in groups to truly thrive. But unlike many other freshwater species, this isn’t a matter of anxiety or confidence. When these fish aren’t in a large group, they quickly turn on each other!

There’s no exact science to determine how many fish are needed to avoid this. But generally, groups of at least 12 are successful. If you have a very large tank, don’t be afraid to get a group of 25 to 50!

In large groups, no single bucktooth will be targeted and killed. Instead, they’ll team up and focus their attention on any other sick or unhealthy fish.

These fish can create a beautiful display of color when they swim together. Highly active, they will zip around the tank to explore and exercise. They may swim in unison, but they will also break away and do their own thing from time to time!

Bucktooth tetras are a highly aggressive fish that’s also very confident in the aquarium. They are not shy like other tetras! As a result, they are always a joy to watch and one of the most entertaining freshwater species you can find.

Bucktooth Tetra Tank Mates

Due to their aggressive nature, bucktooth tetras do best in a single-species tank.

While they’re not the largest fish around, a group of bucktooth tetras can easily take down and kill a bigger fish. Any other fish in the tank will quickly become food.

Author Note: Even cichlids, which are known to be bullies in community tanks, will act like scared targets in the presence of bucktooth tetras!

These fish will make quick work of pretty much any fish. The worst part is that it happens quickly! It only takes a few minutes for another fish to get targeted by a hungry scale-eating bucktooth. Before you know it, the group will swarm and rip the fish up to bits.

Some aquarists have experimented with aggressive bottom-dwelling fish species. But even then, there are never any guarantees about safety. Even if a tank mate were to steer clear of the group, their health would likely suffer from all the stress.

So in summary, it’s always best to keep bucktooth tetras in a single-species aquarium (no matter how confident you are in a potential tank mate combination).


Breeding bucktooth tetras in captivity is possible. However, it’s incredibly rare and quite challenging.

These fish are egg-layers that don’t show any signs of parental instinct. If you want to try your hand at breeding, it’s best to do it in a separate tank.

Set up a small breeding tank with similar water parameters. Add some fine-leaf plants. Bucktooth tetras are egg-scatters. The plants will offer some protection for the eggs.

Author Note: Alternatively, you can install a layer of mesh at the bottom of the tank. With mesh, the eggs can fall through while keeping them separated from the adults.

Condition your fish with a high-protein diet several days before you want to breed them. Then, select a pair and move them to the breeding tank.

To initiate spawning, you can perform a 50-percent water change. Use water that’s a couple of degrees warmer to simulate the changing temperatures of the breeding season.

If you’re lucky, the female will scatter her eggs throughout the tank. When this happens, immediately remove the adults to give the eggs a fighting chance of survival.

The eggs will hatch in two or three days. Once they are free-swimming, provide baby brine shrimp for food. Don’t be surprised if you lose some baby fish. They are prone to cannibalistic behavior, so your young population will dwindle in numbers as they grow.

The best thing you can do is keep them well-fed so that they don’t turn on each other when they get hungry.


Bucktooth tetra care is primarily about learning how to handle the aggression of this species. Failing to plan around this will quickly lead to chaos in your tank!

But if you create an environment that minimizes the aggression of these fish, they can be a complete joy to own. You’ll be treated to a constant display of activity and color.

If you’re still a bit unsure about the possibility of owning this species, feel free to send over your questions! We’re always happy to help our readers.

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