X-ray Tetra

X-ray Tetra facts at a glance

How big is a x-ray tetra?

An adult x-ray tetra measures 5 cm long — about 3% of the height of an average adult person (1.73 m) — and weighs around 1 g, a small fraction of an average adult’s body weight (70 kg).

What is a group of x-ray tetras called?

Explore more animal collective nouns and baby animal names .

A transparent body

The X-ray tetra gets its name from its almost transparent body, through which you can see the spine and a silvery, bullet-shaped capsule that protects its swim bladder. The transparency works as camouflage in sunlit, open water, making the fish hard for predators to pick out.

Safety in schools

X-ray tetras are shoaling fish that feel secure in groups, moving and turning together in loose schools. A school confuses predators and lets the fish spot danger sooner, which is why they are most comfortable and colorful when kept in numbers.

A hardy survivor

Unusually for an Amazon tetra, this species tolerates a wide range of water conditions, including the slightly brackish coastal floodplains where many fish cannot live. That toughness has made it both a successful wild fish and a long-time favorite in home aquariums.

Diet and range

X-ray tetras are omnivores that pick at tiny invertebrates, insect larvae, and bits of plant matter. They live in the rivers and seasonally flooded lowlands of the Amazon and Orinoco basins in northern South America and remain common in the wild.

Did you know? X-ray Tetra facts

• The X-ray tetra is a small, translucent freshwater fish from the Amazon basin whose see-through body reveals its backbone and a silvery swim-bladder capsule.
• The X-ray tetra has a nearly transparent body, so you can see its backbone and a silvery swim-bladder capsule through its skin, as if looking at an X-ray.
• X-ray tetras are tiny, growing to only about 5 cm (2 in) in length.
• They are omnivores that eat small invertebrates, insect larvae, and plant matter, foraging in open water and near the bottom.
• X-ray tetras live in the Amazon and Orinoco river basins of South America, including slightly brackish coastal floodplains.
• Conservation: Least Concern (IUCN).

Diet & feeding

X-ray Tetra feeds primarily as a omnivore (small invertebrates, plant matter).

Adaptations

• The X-ray tetra gets its name from its almost transparent body, through which you can see the spine and a silvery, bullet-shaped capsule that protects its swim bladder. The transparency works as camouflage in sunlit, open water, making the fish hard for predators to pick out.
• X-ray tetras are shoaling fish that feel secure in groups, moving and turning together in loose schools. A school confuses predators and lets the fish spot danger sooner, which is why they are most comfortable and colorful when kept in numbers.

Behaviour & ecology

• The X-ray tetra gets its name from its almost transparent body, through which you can see the spine and a silvery, bullet-shaped capsule that protects its swim bladder. The transparency works as camouflage in sunlit, open water, making the fish hard for predators to pick out.
• X-ray tetras are shoaling fish that feel secure in groups, moving and turning together in loose schools. A school confuses predators and lets the fish spot danger sooner, which is why they are most comfortable and colorful when kept in numbers.
• Unusually for an Amazon tetra, this species tolerates a wide range of water conditions, including the slightly brackish coastal floodplains where many fish cannot live. That toughness has made it both a successful wild fish and a long-time favorite in home aquariums.

Communication

• Lateral-line and visual cues coordinate schooling, courtship, or territorial behaviour.
• Some species produce low-frequency sounds or drumming for spawning or defence.

Habitat & range

Coastal Amazon rivers and floodplains

Ecological role

X-ray Tetra occupies a defined trophic level in aquatic food webs, linking plankton or smaller fish to larger predators.

Conservation status of the X-ray Tetra

Sources & references

This guide is compiled and reviewed against established zoological and conservation references. Key sources for the X-ray Tetra:

• IUCN Red List of Threatened Species

  Conservation status (Least Concern) reflects the IUCN Red List category for Pristella maxillaris.

• iNaturalist — observations & photos

  Search citizen-science observations and community IDs for Pristella maxillaris. Useful for range checks and recent sightings — not a substitute for formal Red List status.

• GBIF — occurrence data

  Global Biodiversity Information Facility species search for Pristella maxillaris. Explore published occurrence records used in range research.

• IUCN Red List — Pristella maxillaris.

  Conservation status (Least Concern) and population trends.

• Animal Diversity Web — Pristella maxillaris. University of Michigan Museum of Zoology.

  Life history, morphology, and range.

• Wikipedia — X-ray Tetra.

  General taxonomy and overview (cross-check primary sources).

• Global Animal Guide editorial standards

  How we research, source, review, and update every guide for accuracy.