Bucktooth Tetra (Exodon Paradoxus): Ultimate Care Guide


The Bucktooth Tetra, Exodon Paradoxus, is a freshwater fish native to the Amazon Basin and Guyana in South America. They are also commonly referred to as Exodon. The earliest record of this fish was made in 1845, but they were not an aquarium trade import until 1932.

Bucktooth Tetras are shaped like most other tetras. They are small fish that have torpedo-shaped (elongated) bodies. They are brightly colored fish. Their main color is metallic silver, but they have hints of yellow, green, and red throughout. Exodons have two distinct black dots, one in the middle of the body and one on the base of the tail. Their fins are transparent with splashes of red, orange, and yellow.

Bucktooth Tetras have unique teeth that are used to rip the scales off of other fish. The teeth do not stick out, but they are outward-facing. The teeth are pointed and sharp so they can get under other fish’s scales to pop them off. While these weapons may sound scary, they are surprisingly difficult to see on the fish unless viewed from close-up.

If Exodons were villains in a fictional story, they would not be the calm, cool assassins of the river. They are more like the really attractive guy who also happens to have a torture chamber in his basement. They don’t hunt fish to kill them outright. Bucktooth Tetras can be violent towards other fish and will swarm the other fish to pick at them until they have no scales left.

Bucktooth Tetras are not shy like other tetras. They are incredibly active fish. Exodons will swim around in groups and break off on their own. The colorful fish give aquarists a bright and joyful show to watch.

Bucktooth Tetra (Exodon Paradoxus)
Bucktooth Tetra (Exodon Paradoxus)

Bucktooth Tetra Care

Bucktooth Tetras can be quite the challenge in an aquarium, so they are recommended for seasoned aquarists.

Water Temperature

They prefer warmer waters since their natural habitat is in the warm South American water. 72 to 82°F will do, with 75°F being preferred.

Water pH

The pH level of the tank should be between 5.5 and 7.0 leaning more toward the acidic side of this range.

Bucktooth Tetra Size

Exodons grow to be between 4 and 5 inches long in aquariums, but they can be up to 6 inches long in the wild. Aquarists have tried to get them to reach the 6-inch mark in captivity, but even with massive tanks and precise feeding strategies, it does not work out very often.

Bucktooth Tetra Food and Diet

In the wild, Bucktooth Tetras eat a lot of scales. They do not supplement their diet with scales, it is the main course. Researchers find scales are about 88% of the fish’s diet. They also eat insects and a small number of plants.

One of the main reasons aquarists are attracted to the Bucktooth Tetra is because of how it feeds. If they are given a cube of food in an aquarium, they will swarm around it and form a feeding ball. Each fish darts in trying to get to the center for its portion of food.

Exodons are scale eaters, but they will live on flake, bloodworm, shrimps, fish flesh, Mysis, and krill. Insects and dried pellets can also be supplemented.

The way Bucktooth Tetras eat has given them another distinct trait. In addition to their special teeth, Exodons will show signs of right or left-handedness. When these fish are looked at from underneath, their heads will tilt to either the right or the left. Left-handed fish attack their prey from the right and right-handed fish attack their prey from the left. They are aggressive fish when it comes to mealtime. They will ram right into their prey in a direct attack.

Bucktooth Tetra Lifespan

These fish are extremely hardy, so if they are properly taken care of, they can last 10 years in captivity.

Bucktooth Tetra Tank Size

These fish like their space. Bucktooth Tetras are active and need a large tank to swim around and explore. They are also shoaling fish, so they do best in large groups. 55 gallons is the smallest recommended size for a group of 12 fish. Having fewer fish can be done, but they do better in groups of 12 or more. Otherwise, they will fight and pick at each other.

Bucktooth Tetra Tank Setup

Exodons do best in tanks that emulate their wild habitat. They live in beach regions in the sandy riverbanks and the floodplain lagoons. They live at the top of the water in big groups in areas where there is not a lot of plant growth.

They do need some plants to zip around and explore in, but they do not spend a lot of time in them. They are good fish to keep with plants though since they will not damage them. Floating plants are great to use in these tanks. Sunken wood pieces, caves, and smooth rocks can be added to the bottom too.

Dark sand is recommended for the substrate. Bucktooth Tetras like to stay between the middle and top of the tank, but they will go to the bottom of the tank for food.

Bucktooth Tetra Breeding

Breeding these fish in captivity is not impossible, but it is rare and very challenging. Exodons have zero parental instinct and will eat their eggs. Potential mates need to be put into a separate breeding tank. This tank can be smaller, but the rest of the water parameters need to stay the same. Bucktooth Tetras scatter their eggs, so adding some fine-leaf plants or a mesh to the tank will add some protection for the eggs.

Fish can be conditioned for breeding by being fed a high protein diet for several days. Select the pair and move them to a breeding tank. Increase the water temperature by just a few degrees to simulate the change in water temperature that happens during their mating season in the wild.

If the female scatters her eggs around the tank, the adult fish need to be removed so the fry will have a chance of survival. The eggs should hatch in 2 or 3 days. When they begin free-swimming, they need to be fed baby brine shrimp. These fish are prone to cannibalistic behavior, so their numbers might decrease as they grow up. Keeping them well-fed will keep them from turning on each other when they are hungry.

Bucktooth Tetra Disease

Bucktooth Tetras can suffer from the common illnesses that plague other freshwater species, but they do not have any unique issues to worry about.

Most commonly these fish will get ich, fin rot, or parasites. The good news is, they are very hardy fish. If treated properly, these diseases can be caught and fixed fairly easily. They do not do well with major temperature or pH fluctuations and a buildup of ammonia and nitrates will cause serious damage to the fish.

Partial water changes every week or two are important to keep a healthy environment for the fish. A powerful filtration system is also a good idea.

Bucktooth Tetra Tank Mates

These fish do not play well with others. They will eat smaller fish and pull the scales off of larger fish that leaves them open to infections.

Due to their highly aggressive nature, Bucktooth Tetras need to be kept in a large group of their own species. They need to be kept in shoals of 12 or more. If they are left in smaller groups, they will pick at each other until they meet a bloody end. The more, the merrier. 50 Exodons can be kept in a tank if it is big enough. When they are in bigger groups, the healthy fish team up and focus on the sick or old fish.

In the wild, the Bucktooth Tetra lives and feasts off of many fish. In captivity, aquarists have tried to find tank mates that will work with the Exodon, but none have worked. A few keepers have had small bits of success with the piranha species, but as a whole, it has failed. Cichlids are known to be bullies in community tanks, but even they will back down from the Bucktooth Tetra.

Many experiments have been done to try and find a good tank mate for the Bucktooth Tetra, but none have worked out. Even if a tank mate was found that could steer clear of the Exodon’s scale attacks, they would likely suffer from a lot of stress. If Bucktooth Tetras are a part of a tank, they need to be the only animal in the tank.

Where Can I Find Bucktooth Tetra for Sale?

Bucktooth Tetras can be found for sale online from specialty fish stores. They are not found in stores like Petsmart or Petco. They range in price from 10.00-14.00 USD per fish. Again, it is highly recommended that these fish be kept in groups of a dozen or more.

Bucktooth Tetras can be a challenging fish to keep in captivity. They are highly aggressive, but beautiful fish to watch swim around the tank.

Fish Laboratory

With decades of collective fishkeeping experience, we are happy to share the fish care tips that we've picked up along the way. Our goal at Fish Laboratory is to keep publishing accurate content to help fishkeepers keep their fish and aquarium healthy.

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