X-ray tetra

The X-ray tetra is a tiny, see-through fish that schools in slow, plant-filled South American waters. At just 4.5 cm long, it is easy to overlook, but its glassy body and touches of red and yellow make it worth a second look.

Also known as: pristella maxillaris, albino pristella, pristella, pristella tetra, water goldfinch, x-ray fish

Many small schooling tetras look alike, but this one's see-through body, showing the backbone inside, is the clearest giveaway among similarly sized fish.

This small fish has a torpedo-shaped body that is almost see-through, with its backbone visible inside. Its scales are silvery-yellow to golden, and its tail fin is red. The dorsal and anal fins carry small spots of black, yellow, and white, and a small round dark spot sits just behind the gill cover.

It lives in slow-moving or still rivers and swamps with thick plant growth across the Amazon and Orinoco basins and nearby coastal rivers in South America. It prefers warm water, between 24 and 28 degrees C.

harmless

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  Texan Tetra

  Astyanax argentatus