X-ray Tetra – Pristella maxillaris

The X-ray tetra, Pristella maxillaris, is one of those aquarium fish that seems modest at first glance, yet quickly becomes a favorite in community tanks. Peaceful, active and visually unique thanks to its translucent body, this small tetra is perfect for both beginners and experienced aquarists. In this article we will explore its origin, care requirements and how to successfully keep it in a beautiful, balanced aquarium. Along the way, we will also show how MB Store can help you with suitable aquariums and aquarium equipment for these fascinating fish.

Origin and Natural Habitat of the X-ray Tetra

The X-ray tetra comes from the coastal river systems of northern South America, especially in Venezuela, Guyana and Brazil. It inhabits slow-flowing rivers, floodplains and areas with dense aquatic plants. These waters are often slightly acidic to neutral, with soft to moderately hard water. The translucent body of Pristella maxillaris is believed to help it blend into the shimmering, light-filled environment of shallow streams.

In nature, X-ray tetras live in large shoals. This schooling behavior is essential for their sense of security and survival, helping them avoid predators and coordinate feeding. When we keep them in aquariums, we should respect this natural tendency by providing a proper group size and a layout that allows them to move freely through the water column.

The natural environment of the X-ray tetra also includes seasonal changes in water levels and chemistry. During the rainy season, rivers flood forested areas, spreading leaves, roots and branches into the water. This creates a rich structure with hiding places, shaded spots and areas of gentle current. Replicating some of these conditions in an aquarium leads to healthier, more colorful and more active fish.

Appearance and Behavior

The X-ray tetra gets its common name from its semi-transparent body, through which the spine and internal organs can be faintly seen, giving it an almost “x-ray” look. The body is generally silvery, with a subtle golden sheen, and the fins display striking colors. The dorsal and anal fins show a combination of black, white and yellow bands, while the tail fin is often slightly reddish, especially in healthy, well-fed individuals.

Adult X-ray tetras typically reach around 4–5 cm in length, making them an excellent choice for small to medium-sized community aquariums. Despite their delicate look, they are quite hardy when kept in stable water conditions and with proper care. This combination of resilience and elegance is one of the reasons they are so popular among aquarists.

Behaviorally, X-ray tetras are peaceful and active. They spend most of their time in the mid-water levels, swimming together in loose schools. When kept in groups of at least eight to ten individuals, they display natural social behaviors: coordinated swimming, gentle chasing and subtle fin displays. In smaller groups, they may become shy and hide more, or conversely become stressed and more susceptible to disease.

These fish are generally non-aggressive and suitable for community tanks. They rarely nip fins and usually ignore other species, focusing on their own group. However, their small size makes them vulnerable to large or predatory fish, so careful selection of tank mates is necessary. With the right companions, X-ray tetras will be active, visible and relaxed throughout the day.

Ideal Aquarium Setup for Pristella maxillaris

To keep X-ray tetras healthy and thriving, it is important to design an aquarium that meets their physical and behavioral needs. For a group of ten individuals, an aquarium with a minimum length of 60 cm is recommended, though more space is always beneficial. MB Store offers a range of aquariums in various sizes and shapes, making it easier to choose a tank that suits both the fish and the available space in your home.

The substrate can be fine sand or smooth gravel. Darker substrates often enhance the colors of the fish, creating a stronger contrast with their transparent bodies and vivid fin markings. A well-structured layout with plants and decorations is crucial. Use a mix of rooted plants and floating plants to provide shade and visual barriers. Plants like Amazon swords, stem plants and floating species such as Salvinia or frogbit all work well.

Hardscape elements, such as driftwood, roots and rocks, help mimic the natural environment of the X-ray tetra. They offer hiding spots and territories, reducing stress and giving the fish a sense of security. Avoid sharp-edged decorations that might damage the delicate fins. The swimming area in the middle of the aquarium should remain open so that the school can move freely.

Lighting should be moderate. Too intense lighting can make these somewhat shy fish feel exposed, especially if the aquarium lacks dense plant cover. With moderate lighting and shaded zones created by floating plants or overhanging decorations, X-ray tetras show more natural coloration and behavior. MB Store also provides suitable lighting systems that can be adjusted to create these conditions, enhancing both plant growth and fish comfort.

Filtration is another crucial aspect. X-ray tetras prefer clean, stable water with gentle to moderate flow. A quality external or internal filter from MB Store’s selection will help maintain good water parameters. Aim for a current that gently moves plants but does not turn the tank into a high-flow environment, which could stress these small fish. Adding a pre-filter sponge over the intake can protect both fry (if present) and small invertebrates.

Water Parameters and Maintenance

Although X-ray tetras are considered relatively hardy, they still require stable, well-maintained water conditions for long-term health. The ideal temperature range is between 24 and 28°C. A reliable heater with an integrated thermostat, available at MB Store, helps maintain this temperature consistently, avoiding sudden fluctuations that can stress the fish.

The pH should preferably be between 6.0 and 7.5, and the general hardness (GH) in the low to medium range. They adapt well to slightly harder water than some other South American species, which makes them more flexible for community aquariums. However, sudden changes in pH or hardness should be avoided. When adjusting water chemistry, it is best to make changes slowly and monitor the effects over time.

Regular water changes are essential. Replacing 20–30% of the aquarium water every week helps remove nitrates and organic waste. Using a gravel vacuum during water changes will also remove debris from the substrate without disturbing the aquascape too much. MB Store offers a variety of water conditioners, dechlorinators and test kits that help you monitor and maintain stable parameters.

It is important to cycle the aquarium fully before introducing X-ray tetras. This means allowing beneficial bacteria to colonize the filter and substrate so they can efficiently process fish waste into less harmful compounds. A properly cycled aquarium shows stable levels of ammonia and nitrite (both at zero), with manageable nitrate levels. Only then is it safe to add sensitive schooling fish like X-ray tetras.

Ongoing maintenance also includes cleaning the filter when necessary, but never too thoroughly and never with untreated tap water. Instead, rinse filter media in a bucket of aquarium water during a water change. This preserves the beneficial bacteria. Good aeration is beneficial too, although the surface agitation from the filter outlet is often enough in most community tanks.

Diet and Feeding

X-ray tetras are omnivorous and have a fairly broad diet. In nature they feed on small invertebrates, insect larvae, zooplankton and plant matter. In the aquarium, they readily accept quality dry foods, such as flakes or micro granules, making daily feeding easy. For a balanced diet, choose foods specifically formulated for small tropical fish, which MB Store offers in different brands and formulations.

Despite the convenience of dry food, variety is key to vibrant coloration and strong immunity. Supplement their diet with frozen or live foods, such as daphnia, bloodworms, brine shrimp and micro-worms. These protein-rich foods are not only nutritionally beneficial but also stimulate natural hunting behaviors, providing mental and physical enrichment for the fish.

Feed small portions two to three times per day, only as much as the fish can consume within a few minutes. Overfeeding leads to uneaten food decaying in the tank, which can quickly degrade water quality and stress the fish. It is better to feed more frequently in smaller amounts than large portions once a day. Observing the school during feeding is also a good way to monitor health; sudden changes in appetite or behavior can be an early sign of illness.

Occasionally offering plant-based foods or spirulina-containing flakes can support digestive health. While X-ray tetras are not strict herbivores, they do benefit from some vegetation in their diet. Remember that a varied, high-quality diet combined with clean water is one of the best forms of prevention against disease.

Tank Mates and Community Compatibility

One of the main attractions of X-ray tetras is their excellent compatibility with a wide range of other small, peaceful fish. Their calm temperament and mid-water swimming zone allow them to coexist with many community favorites. Ideal tank mates include other small tetras, rasboras, peaceful barbs, dwarf gouramis, as well as bottom-dwelling species like Corydoras catfish and small loaches.

When selecting tank mates, avoid large or aggressive fish that might see the X-ray tetra as prey or harass them. Species such as large cichlids, big barbs or fin-nipping fish are poor choices. The delicate fins and small size of Pristella maxillaris leave them vulnerable to bullying, which can cause chronic stress and disease.

Keeping X-ray tetras in groups of at least eight, preferably ten or more, is crucial. In larger shoals, the fish spread any potential aggression among themselves and feel more secure. This results in bolder, more natural swimming patterns and often more intense coloration. A solitary X-ray tetra or a pair will be stressed, withdrawn and much more susceptible to health issues.

Invertebrates, such as shrimp and snails, can also be kept with X-ray tetras, provided the shrimp are not extremely small and there are sufficient hiding places. While adult X-ray tetras usually ignore larger shrimp, very small juveniles may be eaten if encountered. Dense planting, mosses and fine-leaved plants provide shelter and help maintain a harmonious community.

Breeding the X-ray Tetra

Breeding X-ray tetras in the home aquarium is possible and can be very rewarding, although it requires attention to detail and a well-prepared setup. They are egg scatterers, meaning the female lays eggs among plants or over a substrate, and the male fertilizes them externally. The adults do not provide parental care; in fact, they will often eat their own eggs and fry if given the opportunity.

To increase the chances of successful breeding, set up a separate breeding tank, around 20–40 liters in volume. Use soft, slightly acidic water (pH around 6.0–6.8) and a temperature near the upper end of their normal range, around 27–28°C. A fine-leaved plant such as Java moss or a mesh spawning mop should be placed in the tank to catch the eggs. A sponge filter from MB Store can provide gentle filtration without sucking up the tiny fry.

Select a well-conditioned pair or small group of adults, ideally one or two males with several females. Condition them for a couple of weeks beforehand with plenty of live and frozen foods to stimulate egg production. Introduce the breeders to the spawning tank in the evening. Spawning usually occurs in the early morning hours, with the female scattering eggs among the plants while the male follows closely to fertilize them.

Once you observe eggs or notice that the female has become thinner, remove the adults to prevent them from eating the spawn. The eggs usually hatch within 24–36 hours, depending on temperature. The tiny fry absorb their yolk sacs for a few days before becoming free-swimming. At that point, they require very small foods, such as infusoria, liquid fry food or freshly hatched brine shrimp.

Raising the fry demands meticulous water quality and frequent small feedings. Partial water changes with carefully matched water help keep conditions stable. Many aquarists use breeding as an opportunity to refine their skills in water management and learn more about fish development. With patience and the right equipment from MB Store, including small tanks, heaters and sponge filters, successful breeding of X-ray tetras is entirely achievable.

Common Health Issues and Prevention

While X-ray tetras are relatively resilient, poor water quality or stress can lead to disease. Common issues include fin rot, ich (white spot disease) and various bacterial or parasitic infections. Most of these problems are triggered or worsened by unsuitable conditions: high levels of ammonia or nitrite, drastic temperature changes, overcrowding or aggressive tank mates.

Prevention is far easier than treatment. Maintain a regular schedule of water testing and changes, avoid overstocking and quarantine new fish before adding them to your main aquarium. A separate quarantine tank helps you observe new arrivals for signs of illness and treat them if necessary without exposing your existing fish. MB Store supplies the necessary filters, heaters and medications that make quarantine more accessible and effective.

Early detection is essential. Watch for symptoms such as clamped fins, spots, rapid breathing, lethargy, reduced appetite or abnormal swimming. If you notice anything unusual, test your water parameters first. In many cases, simply improving water quality and reducing stress will allow the fish’s immune system to recover. If symptoms persist or worsen, appropriate treatments should be used following the product instructions carefully.

A balanced diet, stable environment and a properly sized, well-maintained aquarium are the foundations of health for X-ray tetras. When their basic needs are met, they can live several years and remain active, colorful and engaging residents of a community tank. Regular observation and prompt action at the first sign of trouble go a long way toward ensuring their long-term well-being.

How MB Store Supports Your X-ray Tetra Aquarium

Successfully keeping X-ray tetras is not only about understanding the species, but also about choosing the right aquarium equipment. MB Store offers complete solutions for beginners and advanced aquarists alike, from small starter tanks suited to compact schools of tetras to larger, fully equipped systems designed for lush, planted communities.

In addition to the aquariums themselves, MB Store provides filters, heaters, lighting systems, substrates and water conditioners tailored to the needs of tropical freshwater fish. With the correct filter and heater combination, you can create a stable, clean environment where X-ray tetras feel secure and display their best colors. Quality lighting and substrates also encourage healthy plant growth, which further benefits the fish by offering shelter and improving water quality.

For those interested in breeding or quarantine setups, smaller tanks, sponge filters and precise heating solutions are also available. This allows you to separate sensitive or breeding fish from the main community aquarium when necessary, improving your control over water parameters and feeding. By combining knowledge of fishkeeping principles with the right products, you can build a harmonious aquarium that highlights the subtle beauty of Pristella maxillaris.

Whether you are setting up your first community aquarium or refining a long-established setup, MB Store’s range of aquariums and accessories helps ensure that both you and your fish can enjoy a stable, attractive and healthy environment. Investing in reliable equipment and thoughtful design is one of the best ways to appreciate the unique charm of the X-ray tetra for years to come.

FAQ – X-ray Tetra (Pristella maxillaris)

How many X-ray tetras should I keep together?
X-ray tetras are schooling fish and must be kept in groups to feel safe. A minimum of eight individuals is recommended, but ten or more is ideal. In small groups they become shy, stressed and more prone to illness. Larger schools show better coloration, more natural behavior and adapt more easily to community aquariums.

What size aquarium do X-ray tetras need?
For a small school of ten X-ray tetras, an aquarium of at least 60 cm in length is recommended. This provides enough swimming space and allows for plants and decorations. Larger tanks offer better water stability and more room for compatible tank mates. MB Store offers various aquarium sizes suitable for these active fish.

Which water parameters are best for Pristella maxillaris?
X-ray tetras thrive at 24–28°C, with a pH of 6.0–7.5 and soft to moderately hard water. Stability is more important than chasing exact numbers, so avoid rapid changes. Regular water changes, good filtration and reliable heaters and test kits from MB Store help maintain suitable, consistent conditions for this species.

Can X-ray tetras live with shrimp and snails?
In a well-planted aquarium, X-ray tetras can coexist with many shrimp and snail species. Adult shrimp are generally safe, though very small juveniles may be eaten if encountered. Providing dense plant cover, moss and hiding spots greatly increases survival for shrimp. Peaceful community setups are usually successful for this combination.

Are X-ray tetras suitable for beginners?
Yes, X-ray tetras are considered beginner-friendly due to their peaceful nature and relative hardiness. They do, however, require a fully cycled aquarium, stable water parameters and regular maintenance. With proper filtration, heating and quality food, all available from MB Store, even new aquarists can keep them successfully and enjoyably.