X-Ray Tetra Species Overview, Care & Breeding Guide

If you want a peaceful fish with interesting looks, the X-ray fish is here to amaze you. Right from its playful schooling nature and elegant moves to the transparent body, everything leaves enthusiasts stunned.

Due to its ability to fit into community tanks and zero fuss with food, the species is loved by novice and seasoned aquarists alike.

So, if you want to bring this buddy home, dive in to know more…

What is X-Ray Tetra Fish?

The X-ray Tetra fish is a freshwater fish with a body that is so transparent that its bones are visible from outside.

OriginAmazon, Orinoco, Guiana costa river drainages, South America
Scientific NamePristella maxillaris
Common NamesX-ray fish, X-ray tetra, Water goldfinch, Pristella tetra, Albino pristella
IUCN Red List StatusLeast Concern
AppearanceTransparent, deep-bodied, silver-yellow glow; yellow, black, and white striped dorsal and anal fins; yellow to red shades on forked tail
Size (Adult)Up to 4.5 cm (1.8 in)
LifespanUp to 3-4 years; 5 years with best care
TemperamentPeaceful, timid, shoaling
Tank LevelTop and middle dwellers
Water Temperature75-82 °F (24-28 °C)
pH Level6-8
Water HardnessUp to 20 dGH
Care LevelEasy
Minimum Tank Size25 gallons for 8-10 fish
Tank EnvironmentSandy substrate, moderate flow, hiding spots, spacious
DietOmnivorous, micropredator
Tank MatesOwn shoal, other similar-sized peaceful species

What is the Natural Habitat of X-Ray Tetra Fish?

The X-ray fish is found in the alkaline and acidic waters of the Amazon and Orinoco basins and the Guiana coastal river drainage.

In the wild, it can also tolerate slightly brackish water. It’s mostly spotted in Venezuela, Suriname, northern Brazil, Guyana, and French Guiana.

In the dry seasons, the fish inhabits clearwater streams and tributaries. But during the rainy season, it returns to the flooded savannah regions and breeds among the vegetated waters.

As per the IUCN Red List of Threatened Species 2020 assessment, the fish is labeled Least Concern.

Which family does X-Ray Tetra Fish belong?

The characin belongs to the Characidae family under the Characiformes order. While its scientific name is Pristella maxillaris, it’s popular by the following names in the aquarium trade:

  • X-ray fish
  • X-ray tetra
  • Water goldfinch
  • Pristella tetra

Fun Fact: Until 2019, the X-ray fish (Pristella maxillaris) belonged to the monotypic genus. Now, there are three notable species in the genus. Besides that, this fish was initially named Pristella riddlei.

How does X-Ray Tetra Fish look?

Pristella tetra with golden sheen

If you want to get this fantastic fish, let’s get to know more about its looks here…

What is the Size of X-Ray Tetra Fish?

In captivity, the X-ray fish grows up to 4.5 cm (1.8 in). Only a few specimens rarely reach 5 cm (2 in).

What is the Color of X-Ray Tetra Fish?

From afar, you can only notice the X-ray tetra’s transparent body and lack of color. However, it actually has a silver-to-yellow shine on its body. Owing to the transparency, you can see its organs and backbone.

There are small yellow stripes at its dorsal and anal fin bases. Further away from the body, the fins have a broad black stripe and are white-tipped.

You can also see a black spot behind its head and yellow to orange or red to pink shades on the tail fin.

Specimens with strong gold sheens are usually given different names – water goldfinch and golden pristella tetra.

There are also other varieties:

  • Albino pristella tetra, aka golden X-ray tetra: It has pink spots and eyes and a much more faded look than the regular one. It’s easier to breed than regular ones.
  • Red belly X-ray tetra: It looks like a regular X-ray fish with pink eyes and pink spots on the body.
  • Balloon X-ray tetra: It has a larger and rounder body than the regular one.

What are the Features of X-Ray Tetra Fish?

The deep-bodied X-ray fish is stockier around the middle region and has a forked tail.

It’s known to have a bony internal structure connecting the swim bladder and auditory system aka Weberian apparatus. Like an amplifier, it helps the fish receive and identify sound waves, which further boosts its sense of hearing.

How is a male X-Ray Tetra Fish different from a female?

The female X-ray fish is known to have a larger body and bulkier abdomen than the male fish. The transparency among the females makes it visible when they have eggs. The slender male has a pointy swim bladder.

Otherwise, both gender looks similar.

What is the behavior of X-Ray Tetra fish in a tank?

X-ray tetra is pretty peaceful and timid. The shoaling fish loves to swim around in Its own group. It doesn’t cause major conflict, but fights within the shoal are normal. The species may struggle to coexist with bigger and boisterous species.

When stressed, it stays hidden. If startled, it darts away to its hiding spots. But if it feels safe, happy, and confident, it swims in the middle and top water columns.

What is the Lifespan of Pristella Tetra?

On average, the X-ray fish can live up to 3-4 years. But in my experience, quality care can extend this to 5 years or longer.

Author’s Note: When the X-ray tetra is stressed, it becomes even more faded. It loses the slight silver or gold shine.

How to care for X-Ray Tetra Fish?

X-ray fish pair

If you’re planning to add this fish to your tank, let’s know everything to provide top-notch care for your pet.

What is the Tank Size of X-Ray Tetra Fish?

Invest in a 25-gallon tank for a group of 8-10 X-ray fish. If you want to build a community tank of peaceful species, upgrade to a bigger tank depending on the needs of all the inhabitants.

What is the water chemistry for X-Ray Tetra Fish?

To keep your tetras healthy, you must pay extra attention to the water quality. So, strictly follow these water parameters at all times.

  • pH Levels: 6-8
  • Water Temperature: 75-82 °F (24-28 °C)
  • Water Hardness: Up to 20 dGH
  • Ammonia: 0 ppm
  • Nitrite: 0 ppm
  • Nitrate: Less than 30 ppm

What is the Tank Environment for X-Ray Tetra Fish?

Your next responsibility is to help your pet fish feel comfortable and at home in your tank. Create the perfect ambiance to achieve that. So, let’s begin…

Which Substrate does X-Ray Tetra Fish prefer?

The ideal substrate for your X-ray fish is dark, fine-grained river sand. Although the fish doesn’t spend much time at the bottom, it’ll help your pet fish stand out in the tank. It also mimics its natural habitat and makes it feel at home.

Which Plants do X-Ray Tetra Fish prefer?

The X-ray tetra doesn’t try to uproot plants so you can create a planted aquarium. Plants also make the fish feel secure and provide shelter. Amazon sword, java moss, and java fern are the most common picks.

What type of Lighting is needed for X-Ray Tetra Fish?

To make the X-ray fish feel comfortable and show off its best features, use dim and subdued lighting. Bright light may make the tetra too timid to come out of its hiding spots. Additionally, put floating plants to disperse the lighting further.

Which Décor does X-Ray Tetra Fish need?

You can use some driftwood branches, dried and debarked common beech, or twisted roots. However, use them in moderation, as your fish needs plenty of space to swim. Especially keep the center of your tank open.

Add dried beech, Catappa, Indian almond, or oak leaves as well. Let the wood and leaves stain the water with a weak tea color. Ensure you replace them every few weeks to avoid rotting and water spoiling.

Add plenty of hiding spots like caves and PVC pipes.

Which type of Filtration does X-Ray Tetra Fish require?

Use a strong filter – like a canister or powerhead filter – to maintain the water quality. Add a pouch of aquarium-safe peat into the filter to maintain preferable pH levels and stain the amber color.

What is the Water Flow Rate of X-Ray Tetra Fish Tank?

This tetra loves to swim in some current. So, maintain a moderate water flow rate in the tank.

Care Tip: Characins have zero tolerance for salty water. This fish is an exception – it inhabits slightly brackish environments in the wild. However, don’t mistakenly put it in a saltwater aquarium. It can handle up to 10% of a regular marine aquarium salinity and up to 1.0002 specific gravity.

What does X-Ray Tetra Fish Eat?

The X-ray fish is a micropredator, i.e., it thrives on a diet of small invertebrates in the wild. In captivity, the fish is an omnivore and makes no fuss with food. It accepts commercial food, live and frozen feed, and also vegetables.

Some great dietary components for it are:

  • Quality dried flake
  • Granule
  • Tablet
  • Pellet
  • Smaller fish
  • Shrimp
  • Red daphnia
  • Brine shrimp
  • Bloodworm
  • Finely chopped vegetables

Feed it regularly, thrice a day, for about 3 minutes for every meal. Make sure you follow the meal routine religiously. Otherwise, the voracious eater may start munching on plant leaves when hungry.

If you keep your mealtimes fixed, your fish will become trained to be more active during that time. Offer different kinds of food to ensure your pet’s good health.

What are the Tank Mates for X-Ray Tetra Fish?

Before adding any other tank mate, ensure you have a shoal of 6-10 or even more X-ray fish, as it’s a shoaling species. Otherwise, a lonely specimen will be vulnerable to diseases due to stress.

The best tank mates for it are:

Which Tank Mates to Avoid for X-Ray Tetra Fish?

The X-ray fish can’t keep up with the following kinds of tank mates:

  • Larger species: They may eat or harass your pet fish.
  • Aggressive species: They’ll stress the timid X-ray.
  • Small species that fit its mouth: They’ll get eaten by the X-ray.
  • Long-finned species: The tetra may try to nip their fins.

What are the Common Diseases for X-Ray Tetra Fish?

The X-ray tetra is vulnerable to most common freshwater fish diseases – like ich, fin rot, and columnaris. Other than that, it also suffers from this:

Disease NameCausesSymptomsTreatment
Skin flukesParasitic InfectionRed spots, excess mucus, breathing issues, flashing, missing scales, poor appetite, tirednessImprove water chemistry, improve diet, administer oral medications, medicated baths, or injections

Quick Tip: The best way to prevent X-ray fish from falling sick is to check the water chemistry regularly and maintain ideal levels.

How to breed X-Ray Tetra Fish?

Although X-ray fish are easy to breed, it’s hard to find compatible pairs. The species is pretty particular while picking mates. The male may also act unresponsive if he doesn’t like the female. You may need several attempts to establish a pair.

It’s also difficult to care for the fry, but the endeavor is not impossible. So, follow these steps to ensure a successful breeding.

1. Breeding Tank Preparation

Prepare a separate 15-gallon tank with dim or no lights. Add floating plants to disperse the light.

Decorate it with fine-leaved plants like Java moss and Myrophyllum and spawning mops for egg-laying.

Incorporate a small air pump or sponge filter with peat and create a gentle flow. Add a protective grid or mesh that allows eggs to pass through but not the adult fish.

Maintain water chemistry as follows:

  • Water Temperature: 79-84 °F (26-29 °C)
  • pH Levels: 5.5-6.5
  • Water Hardness: 1-5 dGH

2. Fish Choosing & Conditioning

X-ray tetras sexually mature when they’re 5-8 months old. They are group spawners. So, separate the group by gender and house them in two different tanks. Or, use an aquarium divider. Keep them separated for about two weeks. Condition them with small live prey.

Pick the three fattest and most active females with visible eggs and the three most bright-colored males.

3. Mating

Introduce all chosen specimens in the breeding tank. It won’t take a lot of effort to make them spawn if there’s a mated pair.

When the female is ready to lay her brood, the male follows behind and externally fertilizes them.

Generally, they spawn the following day – early in the morning. The entire process takes about 2 hours at most. Each wild-bred female may lay about 300-500 eggs. But most available fish are captivity-bred and have much smaller brood.

4. Separation

If you notice eggs, relocate the parent fish group to the main tank. Otherwise, they might prey on the eggs or even their fry.

5. Incubation & Fry Caring

The egg and fry are light-sensitive. So turn off all lights when eggs appear. Eggs hatch within 24-36 hours. Owing to the extremely small size of the fry, it’s challenging to rear them.

The fry live on their egg yolk for a while and then become free swimmers after 3-4 days.

After that, start feeding the fry infusoria for a few days. Once they grow bigger and have a big enough mouth, provide microworm, baby brine shrimp, and crushed flake.

Be extremely careful about the water chemistry. Unsteady parameters can be fatal to the fry.

Breeding Tip: After introducing mating specimens in the breeding tank, check for eggs around the afternoon. If there are no eggs, try the process with another group.

A word from FishInAquarium

The X-ray fish never makes trouble in the aquarium. However, it may often get into friendly fights with its own kind. These interactions are bound to entertain you with their amusing antics.

Moreover, it’s pretty inexpensive, so you can easily get your hands on a bunch of X-rays right away!

If you found this article helpful, share it with other enthusiasts. Have any queries? Send us an email, and we’ll come back to you with an answer!

Minnie B Miller - Professional aquarist and owner of FishInAquarium

About Minnie B Miller

Minnie B. Miller, a professional aquarist and owner of FishInAquarium, has over 8 years of expertise in fish breeding and care, gained through her roles at AquaticTX and Sea Lion Landing. Having honed her skills with various aquatic species, she is dedicated to empowering fellow enthusiasts by sharing her knowledge and experience.