X-Ray Tetra (Pristella maxillaris): Ultimate Care Guide

Common NameX-Ray Tetra, Water Goldfinch, Pristella Tetra, Golden Pristella Tetra
Scientific NamePristella Maxillaris
OriginSouth America / Amazon River
Temperature72F – 82F
Water pH6.0 – 7.5
Sizeup to 1.75 inches

X-Ray Tetra Facts

  • X-Ray Tetras were given their name due to their see-through appearance. Juvenile X-Ray Tetras are even more transparent than mature ones. This transparent coloration serves as excellent camouflage in the murky Amazon water.
  • X-Ray Tetras are a schooling micro-predator that is considered an opportunistic and omnivorous feeder.

X-Ray Tetras inhabit the black waters of the Amazon River in South America. They are a hardy species that can be found in freshwater and brackish waterways throughout South America. They inhabit the inland streams during the dry season, and migrate to the more murky marshland waters during the rainy season. They thrive in areas with dense vegetation and debris where they hunt the shore line for food.

X-Ray Tetra (Pristella maxillaris)
X-Ray Tetra (Pristella maxillaris)

 X-Ray Tetras are small, schooling fish whose markings help them see each other as well as stay together in the murky Amazon waters. X-Ray Tetras are small fish that only group up to 1.75 inches in length. These micro schooling fish, like most fish in the Amazon are opportunistic, omnivorous feeders. This means that they will eat what they can get, both plant and animal matter.

X-Ray Tetras have small, torpedo shaped bodies, with rounded bellies. They have a silvery, transparent coloration. Their dorsal, anal, and caudal fins are yellow and black with transparent tips, while their tail fins are red. They are a stunning and popular fish for the home aquarium due to their looks. They are not quite as see-through as other species, but it is still  a helpful adaptation of effective camouflage from predators.

X-Ray Tetra Care

X-Ray Tetras are considered hardy fish that are easy to care for. They accept and can thrive in a wider range of water parameters which makes them an easy fish to place in a community tank setup without issue. They are somewhat forgiving of changes in their water parameters, and can tolerate these changes without rapidly declining. Do not misunderstand, it is still important to establish regular water parameter checks and correct any issues. X-Ray Tetras are great for beginners to the fish keeping hobby for this reason.

Not only are X-Ray Tetras tolerant of water parameter changes, they are also not picky when it comes to feeding time. In the home aquarium they will readily accept flaked, pelleted, or freeze-dried foods.

Tank Requirements

X-Ray Tetras are schooling fish, and if you are planning on purchasing them for your home aquarium, you will want to make sure that you have enough room for the size of school you wish to have. The good news is that because they are small, they do not require that large of a tank for a small school. To house a small school of 5 X-Ray Tetras, you will need a tank that is at least 20 gallons. X-Ray Tetras are an active species, and if you have more room for a larger tank, then you will be able to keep a larger school while still giving them plenty of room to freely swim about.

X-Ray Tetras are hardy fish that are able to tolerate a wider range of water parameters. This makes them a great fish for beginners as they will not go into a rapid decline if their water parameters are off. This does not mean that you should not perform regular water checks, it only means that they will not go into rapid decline if their water parameters are not correct. They do best when kept at a temperature range of 72F to 82F, and a 6.0 to 7.5 pH.

X-Ray Tetra (Pristella maxillaris)
X-Ray Tetra (Pristella maxillaris)

Food and Diet

Like many fish in the Amazon, X-Ray Tetras are opportunistic and omnivorous micro predators. This means that they will eat whatever they can, plant or animal matter, but they prefer to hunt for their food. In the wild, X-Ray Tetras spend their time searching for food along the shore line, and can be found snacking on small crustaceans, insects, and worms as well. X-Ray Tetras also eat plankton. Pretty much anything small and moving is a possible meal for a hungry X-Ray Tetra. They will eat aquatic plants as well, but their prefered method of feeding is to hunt for their food.

In the home aquarium, X-Ray Tetras will readily accept frozen, live, and flaked foods. They should be fed a high quality, varied diet so that they are sure to receive all the nutrition that they need. Feeding them different foods will help keep them from getting bored of what they are eating. Remember, in their natural environment X-Ray Tetras have a large variety in what they choose to eat. You can supplement their diet with occasional feedings of live foods as well such as Daphnia or Bloodworms. Since they are such voracious eaters, it can be easy to overfeed this species of Tetra. They should be given 2 to 3 meals throughout the day, and only enough food that they can completely consume in 2 to 3 minutes. You will want to make sure that you are feeding them bits of food that are small enough to fit into their tiny mouths.

X-Ray Tetra Size and Lifespan

X-Ray Tetras can only grow up to 1.75 inches in the home aquarium. Some wild specimens have reached the 2 inch mark, but this is not very common. If they are cared for properly, and fed the correct diet with adequate nutrition, you can expect your X-Ray Tetras to live up to 5 years. In the wild, they do not live quite as long.

X-Ray Tetra Tank Setup

When setting up a tank for X-Ray Tetras, you will want to take a look at their natural habitat. X-Ray Tetras come from the Amazon where they migrate from clear waters to murky ones. They enjoy a tank that is heavily planted, and also provides them with plenty of space to hide, explore, and roam. They are active fish that will enjoy as much space as you can give them. A nice sandy substrate will mimic the sandy river bottoms of the Amazon, and lots of plants should be used to decorate their aquarium as well as driftwood and smooth stones. Plants are a great choice as they help filter out ammonia and other waste products from their water.

X-Ray Tetra Breeding

X-Ray Tetras become fully mature and can spawn at around 5 to 8 months old. In the wild, X-Ray Tetras migrate to floodplains to spawn, so setting up a dedicated breeding tank will help achieve similar conditions and trigger them to spawn.

The breeding tank should have a slightly warmer temperature and be heavily planted with dim lighting. It can be difficult to try to pair off your X-Ray Tetras due to their not being much difference between males and females until they are fully mature. The best way to have success in breeding X-Ray Tetras is to have a group of them and let them pair off naturally.

When conditioning your X-Ray Tetras for spawning, you will want to offer them live foods at least twice a day while making sure that their pH is neutral. When the female is ready to spawn, she will lay her eggs among the plants, and the male will come along and fertilize them. Once the X-Ray Tetras are done spawning, you will need to remove them from the breeding tank as they do not provide any parental care to their eggs or young. They will also eat their own eggs and fry.

X-Ray Tetra eggs hatch at around 24 and 36 hours after they are fertilized. They remain connected to their yolk sac for around 3 to 4 days before they become free swimming.

X-Ray Tetra fry feed on insect larvae in the wild, but in captivity, your challenge will be in making sure that the food you offer them is small enough for them to fit in their mouths. You can feed them infusoria, and change it up to brine shrimp when they are a little larger.

How Do X-Ray Tetras Breed?

X-Ray Tetras are egg laying fish. When they are ready to spawn, you will be able see your female X-Ray Tetras growing large in their belly. This is due to them carrying eggs. In the wild, X-Ray Tetras migrate to breed in the dense floodplains. In captivity, you will want to set them up with a breeding tank that closely mimics those conditions.

When the female and male have paired off, the female will then choose to lay her eggs on different plants in the tank, the male will then come after her and fertilize the eggs. X-Ray Tetra females will lay anywhere from 200 to 400 eggs during this time.

X-Ray Tetras are not easy to breed, but of all the Tetra species, they are among the easiest to get to spawn in the home aquarium as long as the right conditions are being met.

How Do you Tell X-Ray Tetra Males from Females?

X-Ray Tetras are fairly difficult to determine male from female until they have reached maturity. X-Ray Tetras reach maturity at around 5 to 8 months old, and around this time, you will be able to determine which X-Ray Tetras are females due to their enlarged, egg filled bellies. Fully mature females are also slightly larger. Due to there not being much difference between the two, you will have greater success of getting a breeding pair if you have a group of juvenile X-Ray Tetras and let them mature together and naturally pair off.

X-Ray Tetra Disease

X-Ray Tetras are considered a hardy fish, but they are still susceptible to many of the same ailments as other freshwater fish. Like most fish in captivity, their health and longevity is directly related to how well they are kept. If X-Ray Tetras are not kept in adequate conditions, their health will suffer. It is more important to prevent these ailments from happening than it is to try to cure them once they do. You should perform regular water checks and changes to ensure that your fish are being kept in the ideal water parameters.

Here are some of the disease that can affect X-Ray Tetras:


Ich is a parasitic disease that shows up on the body of the affected fish in white, blotchy spots. You will be able to visibly see if you have a fish that is affected by Ich. If left untreated, it will spread all over the body of the fish and into the fish’s gills. Once it gets into their gills, it can quickly render the fish unable to gather oxygen from the water, and they will suffocate. Ich is very contagious. It can be easily carried over to your aquarium from affected fish and even decor. It is important to quarantine any new additions to your tank for at least 2 weeks to be sure that you are not contaminating your other fish. If it is caught early enough, Ich can be treated.

Skin Flukes

Fluke is a common name for a type of parasitic flatworm that can live on the skin or in the gills of your fish. Flukes attach themselves to the skin or gills of the fish. Skin flukes can be treated, but can cause death if left untreated.

Parasitic and Bacterial Infections

If caught early on, parasitic and bacterial infections can be cured in X-Ray Tetras.

Are X-Ray Tetras Aggressive?

X-Ray Tetras are considered a peaceful species that can be placed into a community tank setup without much issue. They are an active fish that will occasionally nip at the fins of slower fish with long, flowy fins.

How Many X-Ray Tetras Should Be Kept Together?

X-Ray Tetras prefer to be kept in a school. They should be kept in a grouping of at least 6 so that they are comfortable enough to display their interesting grouping behavior. X-Ray Tetras do not do well as a lone fish of their species in the home aquarium as they will quickly become stressed and ill.

Tank Mates for X-Ray Tetras

X-Ray Tetras are a peaceful fish that can easily go into a community tank setup as long as they are being kept with fish that have a similar nature and requirements. Other tetras are great tank mates, as well as some Dwarf Cichlids, Plecos, and Corydoras. When choosing tank mates, make sure that they occupy different spots in the water column of your tank to avoid overcrowding. Betta Fish can also be great tank mates for X-Ray Tetras as long as there is plenty of room, and your X-Ray Tetras are not nipping the fins of the Betta.

You will want to avoid placing them with fish that are larger, territorial, or will out compete them for food. You will also want to avoid any fish that could potentially see you X-Ray Tetras as a meal. X-Ray Tetras can become stressed and ill if they are housed with fish that are not compatible. Keep in mind that although they are peaceful fish, X-Ray Tetras can be fin nippers for fish that have long, flowy fins and are slower moving like Angelfish.

With all new additions to your community setup, you will want to monitor them closely to make sure that they are getting along and that you can correct any issues as they arise before they become detrimental to the fish.

Where Can I Find X-Ray Tetra For Sale?

X-Ray Tetras can be found at pet stores, and from breeders online for around $3 per fish. Keep in mind that they need to be kept in a grouping of at least 6.

Wild Type X-Ray Tetra

Wild Type X-Ray Tetras are simply X-Ray Tetras that come from the wild instead of being bred in captivity. Their needs and requirements are the same as well as their temperament, but Wild Type X-Ray Tetras can be a little more picky when it comes to the food they eat.

Red Belly X-Ray Tetra

Red Belly X-Ray Tetras are similar to Wild Type X-Ray Tetras except they have bright red bellies and red tips on their fins. They have the same needs as other X-Ray Tetras, and can cohabitate peacefully.

Albino X-Ray Tetra

Albino X-Ray Tetras still have a transparent look to them, but they are more dull. They have pink eyes, and pink spots on their bodies as well. They are still the same as X-Ray Tetras, it is just their look that is different.

Balloon X-Ray Tetra

Balloon X-Ray Tetras have much larger, more rounded bodies compared to the regular X-Ray Tetra. They have roughly the same requirements, and temperament to the regular X-Ray Tetra, just in a much rounder body.

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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