Pristella maxillaris, the only species in the genus Pristella, is commonly known as the X-ray fish or X-ray tetra because of its translucent body. It is a widely distributed and adaptable fish, found in the Amazon and Orinoco basins and coastal rivers in the Guianas in both acidic and alkaline waters. Unlike most other characins, it is tolerant of (and sometimes found in) slightly brackish water. It is small (up to around 5 cm or 2.0 in length) and lives in large groups, and males can be distinguished from females by being smaller and thinner than the females. Like most other tetras, it feeds primarily on small insects and planktonic animals

X-Ray Pristella Tetra

The X-ray fish or X-ray tetra (Pristella maxillaris) is a type of fish in the Characidae family. This is the only species of the Pristella type. The fish is a perfect choice for beginners. It is very undemanding and can live in water with various parameters. In an aquarium, the length of the fish does not exceed 4.5-5 cm (1.77-2 inches).

Common Names: X-Ray Tetra, Pristella Tetra
Origin / Habitat: Amazon River, South America
Care Level: Easy, good for the freshwater fish beginner
Adult Size: Usually about 1″ but it can grow to up to two inches (5 cm).
Life Span: can live five years old.
Tank Size: about 10-20 gallons for the healthy school of pristella tetras. Pristellas are very social. To thrive, pristella tetras must live in groups of five or more. 
Water Parameters: the pH of 6-8
Water Hardness: 6-20 °d
Temperature: Between 75-82 °F or 24-28 °C)


Peaceful, active, and a good community fish. Will school in groups of 6 or more. Other fish use this fish as a spotter fish; if there is a predator about, these fish will spot it first. Therefore, other more timid fish will come out into the open more if you put these fish in your tank. Useful also to the aquarist as an indicator fish. If they are closely packed together, then they are alarmed and feel threatened. Usually, if they are settled, they will disperse over your tank.

In Aquarium

The fish is simple and durable. It can adapt to various water parameters. There are no special requirements regarding tank decorations, and it depends only on the financial possibilities and imagination of its owner or the demands of your tank mates.
This is a school fish, so to make sure the fish is comfortable, you should keep it in a school of 6 species in a 50-70 liter (11-15 gallon) capacity tank.
The tank should be planted with tank plants to create shelters for the fish, and the floating plants will also be of some use, but don’t forget to leave some free space in a tank for the fish to swim.

Tank Mates

Pristellas are non-aggressive and live well in community tanks. Avoid keeping them with large predator species; their small size makes them easy prey. Pristellas is a peaceful and school fish; keep them in a group of at least 6–10 species. The fish does not like loud and overly active tankmates, but it is perfectly compatible with neon tetra, zebrafish, cherry, Guppies, Mollys, or other types of Tetras. 


The pristella tetra is a true omnivore. In nature, they feed on small insects. In our aquarium, we can offer commercial foods as a base diet, Complete in the form of flakes or granules with vegetable content. As a complement, we can choose brine shrimp, red larva, or freeze-dried food. It is a fish that feeds on the surface. Therefore, the remains that can remain of the food and fall to the bottom, we must remove them to avoid their decomposition in the water.


The female is fatter and larger than the male fish, has a rounded body, while the male is thinner, and its abdomen tapers towards the tail stem.
Pristella tetras won’t usually breed by “accident,” but you may get lucky.
It is best to use a previously prepared breeding aquarium. In the first place, we must cover the surface of the aquarium with some floating plants. On the other hand, the soil must be densely planted with some covering plant. Finally, more or less half of the aquarium is very well planted with Cabomba Carolina, for example. The water of medium hardness and neutral pH is good for fish farming. The temperature of the water in the tank should be 25 – 26 °С. A tank of 5-6 liters capacity and less can be used as a spawning tank.
The pair of fish in the tank will begin to spawn in the morning of the next day. If the spawning process is delayed, keep the fish in a spawning tank for another 1-2 days.
If you wish, you can feed the fish a little. For example, give 3-4 bloodworms or chorea for each fish. The eggs are small, transparent, and not sticky. After the spawning is over, you need to put the breeders back in the community tank and leave the eggs for 5-6 days.
Juveniles of the X-ray fish require regular feeding. On the sixth day, give them their first meal. In spring, summer, and autumn they will be pond microorganisms (daphnia, cyclops nauplii), and in winter, you need to prepare infusoria in advance.
In one week, you can feed the juveniles larger live foods: brine nauplii, cyclops, and daphnia. Kids also eat vinegar eels. Later, you can increase the size of the food.
Juvenile X-ray fish grow relatively slow. At the age of 6 months, they become 2.5-3 cm long and reproductive.

Gold Pristella tetra fish
Gold Pristella tetra fish

information from wiki/Pristella_maxillaris

By fishexp