X-Ray Tetra

An In-Depth Guide to the X-Ray Tetra: The Perfect Beginner’s Fish

Among the vast array of tropical fish available to hobbyists, few combine unique beauty, peaceful behaviour, and remarkable hardiness quite like the X-Ray Tetra (Pristella maxillaris). Often sold under the name Pristella Tetra, this small fish is an enduring favourite and an excellent choice for both beginners and seasoned aquarists looking for a reliable and attractive community fish.

This detailed guide will explore everything you need to know to provide the best possible care for these fascinating fish, from their adaptable nature in the wild to creating the perfect environment for them to thrive in your home aquarium.

Natural Habitat and Origins

The X-Ray Tetra hails from the coastal rivers of South America, including the vast Amazon and Orinoco river basins in Brazil, Guyana, Venezuela, and French Guiana. What makes them particularly interesting is their incredible adaptability. Unlike many tetras that are restricted to specific ‘blackwater’ or ‘clearwater’ environments, the Pristella Tetra can be found in a wide range of habitats. They are tolerant of both acidic blackwater streams, stained with tannins from decaying leaves, and more alkaline, clear waters. This natural resilience is a key reason for their hardiness in the home aquarium.

A Truly Unique Appearance

The common name “X-Ray Tetra” is derived from the fish’s most striking feature: its semi-transparent body. The flesh has a yellowish, silvery sheen, but is translucent enough to allow the fish’s backbone to be clearly visible, creating a fascinating ‘x-ray’ effect.

While the body is subtle, the fins provide a stunning contrast. The dorsal and anal fins are marked with a distinct three-stripe pattern of bright yellow, bold black, and brilliant white. This flash of colour, combined with a reddish tail, makes a school of active X-Ray Tetras a captivating sight.

There is also a popular “Golden” or albino variant, which lacks the dark pigments and has a more opaque, golden-hued body while retaining the signature fin markings. An adult X-Ray Tetra will reach a size of around 4-5 cm (1.5-2 inches), and with proper care, can live for 3 to 5 years.

Setting Up the Ideal Aquarium

Thanks to their adaptable nature, setting up a tank for X-Ray Tetras is straightforward. They are not overly demanding, but providing them with a well-thought-out environment will ensure they are healthy and display their best behaviours.

Tank Size and Schooling

The most critical factor in keeping any tetra is to respect its schooling nature. A single X-Ray Tetra will be stressed, shy, and prone to illness. They must be kept in a group to feel secure.

• Minimum School Size: A group of at least 6 is essential, but a school of 8-12 or more will be much more active and visually impressive.
• Minimum Tank Size: For a small school, a tank of at least 45-60 litres is recommended. This provides adequate space for swimming and ensures the water volume is stable.

Water Parameters: A Forgiving Nature

As mentioned, X-Ray Tetras are exceptionally tolerant of a wide range of water conditions, which is why they are so highly recommended for beginners. The key is to maintain stability and avoid any sudden, drastic changes.

Tank Setup and Decoration

To make your tetras feel secure, a planted tank is ideal.

• Substrate: Any fine gravel or sand is suitable. A darker substrate will help their colours stand out and make them feel less exposed.
• Plants and Décor: They will appreciate live plants like Java Fern, Anubias, and Cabomba to provide cover and hiding places. Include some open swimming space in the middle of the tank. Driftwood can be a great addition, especially if you wish to create a more natural, blackwater-style setup.
• Lighting: Standard aquarium lighting is perfectly fine. They are not as shy as some other tetra species but will appreciate some shaded areas provided by plants or decor.

Diet and Feeding

X-Ray Tetras are omnivores and very easy to feed. In the wild, they feast on small insects, worms, and crustaceans. In the aquarium, they will readily accept almost anything offered.

• Staple Diet: A high-quality flake food or micro-pellet should be the foundation of their diet.
• Supplements: To promote the best health and colouration, provide a varied diet. Offer frozen or live foods like daphnia, brine shrimp, and bloodworms a few times a week.
• Feeding Schedule: Feed a small amount that can be consumed in under two minutes, once or twice a day.

Behaviour and Suitable Tank Mates

This species is the definition of a model community fish. They are peaceful, active, and tend to occupy the middle and top levels of the aquarium. Because they are not aggressive, their tank mates must also be peaceful.

Excellent Tank Mates Include:

• Other small, peaceful Tetras (Neons, Cardinals, Rummy Nose)
• Rasboras (Harlequins, Galaxy)
• Corydoras Catfish
• Dwarf Gouramis
• Livebearers like Guppies, Mollies, and Platies
• Small Loaches (e.g., Kuhli Loaches)

Avoid housing them with large, predatory, or aggressive fish, such as most Cichlids, which would easily intimidate or eat them.

Breeding X-Ray Tetras

For those looking to try their hand at breeding egg-scattering fish, the X-Ray Tetra is one of the easier species to start with. To trigger spawning, a separate breeding tank should be set up with soft, acidic water (pH 6.0-6.5) and fine-leaved plants like Java Moss or a spawning mop. The well-conditioned pair (females are rounder and fuller-bodied than males) will typically scatter several hundred eggs. The parents should be removed immediately after spawning to prevent them from eating the eggs.

Conclusion

The X-Ray Tetra is a truly exceptional aquarium fish. It offers a unique and subtle beauty that stands out in any community setup. Its peaceful disposition, active nature, and, above all, its remarkable hardiness make it an ideal choice for anyone new to fishkeeping. By providing a stable environment and the company of its own kind, you can easily enjoy this resilient little gem for years to come.