The Pristella Tetra is a perky little fish that is social, friendly, and very easy to care for!

The Pristella Tetra Pristella maxillaris is a very pretty little characin. It’s known as the X-Ray Fish because its silvery yellow body is quite transparent. It has striking fin coloration. Its dorsal and anal fins have white tips and a striking stripe pattern of a yellow stripe followed by a black stripe. The tail fin is either red or pink. A popular albino variety has also been developed that is more subdued in color overall, but has pink eyes and pink spots. Other common names that describe this beauty include Golden Pristella Tetra, Water Goldfinch, X-ray Tetra, and Pinktailed Tetra.

This popular aquarium fish is the only species in the Pristella genus, and all specimens available in the hobby are commercially bred. In nature the Pristella Tetra inhabits the northeastern coastal waters of South America. During the dry season it lives in streams and tributaries. Then during the rainy season, it moves with the rising waters onto the savannah, where it spawns among the flooded vegetation.

The Pristella Tetra is an excellent fish for the beginner. It is extremely hardy and undemanding and not at all choosy about water type. In nature, it is found in brackish water as well as soft water. It can even withstand very hard water, though it will do best in soft. A dark substrate and subdued lighting will show off the X-Ray Fish at its best and enhance its colors. However, this tetra will not get its full color in hard water or under bright light.

The Pristella Tetra is easy to keep in other respects as well. It is a peaceful community member and is a fairly prolific breeder, though the tiny fry can be tricky to rear. It’s a very active schooling fish, so needs a 15 to 20 gallon aquarium, but is harmless to other fish and plants. A school of 6 or more of these characins is really striking when maintained in a heavily planted aquarium.

Scientific Classification


Pristella Tetra – Quick Aquarium Care

Aquarist Experience Level:Beginner
Aquarium Hardiness:Very hardy
Minimum Tank Size:15 gal (57 L)
Size of fish – inches1.8 inches (4.50 cm)
Temperature:74.0 to 82.0° F (23.3 to 27.8&deg C)

Habitat: Distribution / Background

The Pristella Tetra Pristella maxillaris was described by Ulrey in1894. This species is not listed on the IUCN Red List. They are found in South America in Venezuela, British Guyana, lower Brazilian Amazon, Orinoco, and coastal river drainages of the Guianas. Other common names they are known by include X-Ray Fish, Golden Pristella Tetra, Water Goldfinch, X-ray Tetra, and Pinktailed Tetra.

They inhabit coastal waters that are often brackish. During the dry season, this tetra lives in clearwater streams and tributaries, but once the rainy season comes, the Pristella migrates into the flooded areas of the savannah to spawn in the thick vegetation. They swim in schools in densely vegetated swamps where they feed on worms, small crustaceans, and insects.

  • Scientific Name: Pristella maxillaris
  • Social Grouping: Groups
  • IUCN Red List: NE – Not Evaluated or not listed


The Pristella Tetra or X-Ray Fish is a deep-bodied tetra species. This fish will generally reach about 1 3/4 inches (4.5 cm) in length and has a lifespan of about 4 to 5 years, or even longer. Its silvery to yellowish body features a large spot on the dorsal and anal fin, and a reddish tail. The dorsal and anal fins start with a yellow stripe that changes to a black stripe and ends at a white tip. This is a very striking tetra.

This is a very striking tetra. it is also called X-ray Tetra and Pinktailed Tetra, and specimens that have a stronger golden cast inspired the common names Golden Pristella Tetra and Water Goldfinch.

A popular albino variety has also been developed. The Albino Pristella Tetra, also known as the Golden X-ray Tetra, has pink eyes and pink spots, but a more washed-out body coloration. The albino version is even easier to breed than the natural X-Ray Fish, which may explain its popularity.

  • Size of fish – inches: 1.8 inches (4.50 cm)
  • Lifespan: 5 years – These fish have a lifespan of 4 to 5 years or more.

Fish Keeping Difficulty

The Pristella Tetra is a hardy fish that is great for the beginning fish keeper, and all available specimens are commercially bred. This mass-produced fish is adaptable and will do well in most tank setups, within reason. Keep their water quality high with a good current, and these fish will do great.

  • Aquarium Hardiness: Very Hardy
  • Aquarist Experience Level: Beginner

Foods and Feeding

Since they are omnivorous, the X-Ray Tetra will generally eat all kinds of live, fresh, and flake foods. To keep a good balance, give them a high quality flake food every day. Feed brine shrimp (either live or frozen) or blood worms as a treat. These tetras like several feedings a day, but offer only what they can consume in 3 minutes or less at each feeding.

  • Diet Type: Omnivore – This fish should be fed a rich and diverse diet to promote good coloration.
  • Flake Food: Yes
  • Tablet / Pellet: Yes
  • Live foods (fishes, shrimps, worms): Some of Diet
  • Vegetable Food: Some of Diet
  • Meaty Food: Some of Diet
  • Feeding Frequency: Several feedings per day

Aquarium Care

The Pristella Tetra is easy to care for provided their water is kept clean. Aquariums are closed systems, and regardless of size, all need some maintenance. Over time, decomposing organic matter, nitrates, and phosphate build up, and water hardness increases due to evaporation. To combat these ever-changing conditions, water should be replaced on a regular basis, especially if the tank is densely stocked. At least 25 to 50% of the tank water should be replaced every other week.

  • Water Changes: Bi-weekly

Aquarium Setup

These fish are fairly hardy, and a school of 6 will do best in about a 15 to 20 gallon aquarium. The aquarium should be heavily planted around the sides and back and have plenty of open water for swimming in the front. A few hiding places would also be appreciated. These fish like a moderate amount of current. Add a canister filter or powerhead to create the proper current. The tank should have moderate to dim lighting.

A biotype setup is a great choice for this tetra and is very easy to put together. For the substrate, use a river sand with some driftwood and twisted roots scattered for cover. Add a few handfuls of dried leaves, and remove and replace them every few weeks. To give these fish a real feeling of nature, add some aquarium-safe peat to the filter to simulate the black waters of their natural environment.

As a rule, characins do not tolerate salty water, but the Pristella Tetra is an exception. This is one characin species that naturally inhabits a variety of water conditions, including slightly brackish water that is mineral-rich and has an alkaline pH. Still, its tolerance of salt is not high. It can tolerate a salinity that is about 10% of a normal saltwater tank with a specific gravity of less than 1.0002. If the specific gravity is not kept below 1.003, they will die.

  • Minimum Tank Size: 15 gal (57 L) – A 15-gallon tank is the smallest size that could house the small school this fish requires to be comfortable.
  • Suitable for Nano Tank: Yes
  • Substrate Type: Any
  • Lighting Needs: Moderate – normal lighting
  • Temperature: 74.0 to 82.0° F (23.3 to 27.8&deg C)
  • Range ph: 6.0-8.0
  • Hardness Range: 2 – 30 dGH
  • Brackish: Sometimes – It can tolerate a low salinity brackish tank that is about 10% of a normal saltwater tank, a specific gravity of less than 1.0002.
  • Water Movement: Moderate
  • Water Region: All – These fish will swim in all areas of the aquarium.

Social Behaviors

Pristella Tetra are very peaceful and good community fish. They are ideal for a community aquarium with other peaceful fish. They can be kept in large schools and will do best if kept in a school of at least 6 individuals. Tetras can be easily spooked into hiding, so situate the tank appropriately. The best tankmates for this fish are other small tetras, pencil fish, Corydoras, small rasboras, most livebearers, and loaches.

In a slightly brackish water aquarium, they can be housed with Kribensis CichlidsPelvicachromis pulcher, Orange Chromide Cichlids Etroplus maculatus, small gobies and other small non-predatory fish.

  • Venomous: No
  • Temperament: Peaceful
  • Compatible with:
    • Same species – conspecifics: Yes – This fish should be kept in a school with a minimum of 6 individuals, but more are better.
    • Peaceful fish (): Safe
    • Semi-Aggressive (): Threat
    • Aggressive (): Threat
    • Large Semi-Aggressive (): Threat
    • Large Aggressive, Predatory (): Threat
    • Safe
    • Shrimps, Crabs, Snails: Safe – not aggressive
    • Plants: Safe

Sexual differences

The male is more slender with a sharply-pointed swim bladder. The female is more rounded, and you can actually see the eggs in a mature female.

Breeding / Reproduction

Pristella Tetras are egg layers and moderately easy to breed. The hardest part is finding a compatible pair. They seem to be picky about their partners, and sometimes the male is just unresponsive. The female can spawn 300 to 400 eggs, but commercially-bred individuals may have smaller broods. The commercial practice of feeding fry foods laced with hormones to promote fast growth can result in low fertility. In the home aquarium, the only other challenge is rearing the tiny fry.

A 10-gallon spawning tank is adequate, and a good breeding temperature is 75 to 78.8° F (24 to 26° C). The water should be soft and slightly acidic with a pH of 6.5 to 7 and hardness of 4° dGH or less. There needs to be fine-leaved plants such as Myrophyllum, java moss, or artificial spawning grass, so the female has a place to deposit the eggs. A layer of mesh works, too, if it is wide enough for eggs to pass through but small enough to keep parents out. The tank should be dimly lit. Adding floating plants also helps shield the light. A small, air-powered sponge filter is needed for filtration and will provide a gentle water flow. Filtering the water through aquarium-safe peat is also helpful.

They can be spawned in groups containing about 6 individuals of each sex, or for the best productivity, they can be spawned in pairs. To optimize success, it’s best to condition the males and females in separate tanks prior to breeding. Feed them a rich diet of small, live foods for several days. Select a breeding pair or small group and transfer them into the breeding tank in the evening. A mature female’s belly will become nicely rounded when she is full of eggs. Choose males that are the most colorful.

They typically spawn the following morning. If no eggs appear within a day or two, remove them and try a different pairing. Once a successful spawn has been achieved, remove the parents, or they will eat the eggs. The eggs will hatch in approximately 24 to 36 hours, and the fry will be free-swimming 3 or 4 days later. The fry are very tiny, which makes them difficult to rear. For the first few days, feed them infusoria-type foods until they are large enough to feed on microworm or brine shrimp nauplii. See Breeding Freshwater Fish: Characins for a general description of breeding processes, and see Fish Food for Fry for information about types of foods for raising the young.

  • Ease of Breeding: Moderate – It may take several attempts before a compatible breeding pair is established.

Fish Diseases

The Pristella Tetra is very hardy, and disease is not usually a problem in a well-maintained aquarium. That being said, there is no guarantee that you won’t have to deal with health problems or disease. Anything you add to your tank can introduce disease. Not only other fish but plants, substrate, and decorations can harbor bacteria. Take great care and make sure to properly clean or quarantine anything that you add to an established tank so as not to upset the balance.

A good thing about the X-Ray Fish is that due to their resilience, an outbreak of disease can often be limited to just one or a few fishes if dealt with at an early stage. When keeping more sensitive types of fish, it is common for all fishes to be infected even before the first warning signs can be noticed. The best way to proactively prevent disease is to give your Pristella Tetra the proper environment and a well-balanced diet. The more closely their environment resembles their natural habitat, the less stress the fish will have, making them healthier and happier. Stressed fish are more likely to acquire disease.

As with most fish, they are prone to skin flukes, parasitic infestations (protozoa, worms, etc.), ichthyobodo infection, parasitic infestations (protozoa, worms, etc.), bacterial infections (general), and bacterial disease. Aquarists should read up on common tank diseases. Knowing the signs and catching and treating them early makes a huge difference. For information about freshwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.


The Pristella Tetra is readily available and moderately priced. It is also commonly sold as the X-Ray Fish, Golden Pristella Tetra, and X-ray Tetra.



Featured Image Credit: slowmotiongli, Shutterstock