XRT X-Ray Tetra

The X-ray tetra (Pristella maxillaris), also commonly known as the X-ray fish or golden pristella tetra, is a small, highly adaptable freshwater fish native to South America. Famous for its translucent body that visibly exposes its backbone and internal organs, it is an exceptionally popular and hardy choice for aquarium hobbyists.

Appearance & Features

• Translucency: Their namesake transparent flesh lets you observe their skeletal structure and the silver protective sac enclosing their internal organs. [1, 2]
• Fin Coloration: While the body is see-through, their striking fins feature bold stripes of bright yellow, black, and white, contrasted by a soft reddish-pink tail. [1, 2]
• Size: They are a dwarf species, typically reaching a maximum length of 3.5 to 5 cm (1.5 to 2 inches). [1, 2, 3]
• Acoustic Hearing: X-ray tetras possess a unique bony structure called the Weberian apparatus. This system transmits sound waves through their vertebrae directly from the swim bladder to the inner ear, giving them incredibly sharp hearing to avoid predators. [1]

Natural Habitat

Wild populations are widely distributed across the Amazon and Orinoco basins, as well as coastal rivers in Venezuela, Guyana, Suriname, French Guiana, and northern Brazil. They are highly adaptable to seasonal changes. During the dry season, they inhabit clearwater streams, but once the rainy season begins, they move deep into flooded marshes and savannahs to spawn among submerged plants. Uniquely among characins, they are highly tolerant of salinity and can occasionally be found in brackish coastal waters. [1, 2, 3, 4]