X is for X-Ray Tetra

Beneath a layer of translucent skin and faint, silvery scales, the spine of this tetra species is clearly visible.

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If you look closely, you can see where the name of the X-ray tetra originated. Beneath a layer of translucent skin and faint silvery scales, the spine of this tetra species is clearly visible. The combination of color and translucency is mesmerizing as this fish swims and helps it avoid detection from predators.

Illustration for X is for X-Ray Tetra with 3 Tetras Swimming in front of Seaweed

Not only is this fish visually unique, but this visible bony structure, called the Weberian apparatus, helps pick up sound waves. This contributes to the X-ray tetra's impressive hearing abilities. Sound waves are transmitted through the fish's vertebrate, received by its swim bladder and then travel to its inner ear. These stellar skills help the X-ray tetra avoid predators and locate food sources within its habitat.

Native to the coastal waters of Venezuela, Guyana, Suriname and northern Brazil, this species of fish has successfully adapted to its environment. The climate of this region experiences both rainy and dry seasons, and the X-ray tetra can thrive in both. During the dry season, these fish swim in the clearwater streams and tributaries near the coastline. Upon the arrival of the rainy season, these fish press inward to inhabit the flooded marsh areas, where they breed among the submerged vegetation. As an omnivorous species, these fish munch on the vegetation that surrounds them during the rainy season, as well as insects, small crustaceans and worms.

X-Ray Tetra in Sea Grasses

The livelihood of the X-ray tetra is dependent upon its environment and the cyclical relationship it has developed with the rainy and dry seasons. Due to this dependency, the greatest threats to the X-ray tetra are water pollution and climate change. Increasing industrial activity in its range led to a decrease in water quality, which has contributed to population decline. Additionally, habitat loss because of climate change threatens to thwart the delicate balance the X-ray tetra has woven between the rainy and dry seasons of the Amazon.

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