X-ray fish
X-ray fish, scientifically known as Pristella maxillaris, are small, transparent freshwater fish native to the rivers and streams of South America. First discovered in 1907, these characin fish are notable for their clear bodies, which allow visibility of their bones, muscles, and organs, earning them the name "x-ray fish." Typically growing to about two inches (six centimeters) long, they breathe through gills and rely on water for oxygen, as they do not possess lungs. X-ray fish are social creatures, living in schools and using their various fins to navigate through the water effectively.
This species mainly feeds on smaller aquatic animals, including worms, insects, and crustaceans, making it carnivorous. While specific breeding patterns are not well-documented, spawning occurs when females scatter eggs in the water, which are then fertilized by males. The young fish hatch from jelly-like eggs and join their schools. With a lifespan of two to five years, x-ray fish are popular in the aquarium trade and are not considered threatened, reflecting their adaptability and resilience in various environments.
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X-ray fish
The x-ray fish is native to South America. X-ray fish were first discovered in 1907 shortly before the aquarium was built at the London Zoo. When the aquarium was finished, the world was introduced to these small, transparent, or clear, characin fish.
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Characidae
Genus: Pristella
Species: Maxillaris
X-ray fish were given the name x-ray in honor of their transparent, or clear, bodies. Their bones, muscles, and organs can be seen clearly through their skin, as though an x-ray had been taken of their bodies. X-ray fish generally grow to be about two inches (six centimeters) long.
Like other characins, x-ray fish breathe through gills. Since they do not have lungs and cannot process oxygen from the air, like humans, x-ray fish have to find the oxygen they need from the water in which they live. X-ray fish take water into their mouths, keep the oxygen they need, and breathe out what they do not use.
X-ray fish inhabit the freshwater rivers and streams of South America. Like many other small characins, x-ray fish live in groups called schools. These schools of fish move through the water by the use of their many fins. Each x-ray fish moves its caudal, or tail, fin from side to side to help propel it though the water. It also moves its pectoral, or side, fins to help paddle it through the water. As it is paddling and being propelled, it remains balanced by the use of its dorsal and anal, or back and belly, fins.
Schools of x-ray fish spend much of their time hunting for prey. These small, transparent fish are carnivorous. This means they live on a diet of only meat. X-ray fish mainly prey upon animals even smaller than themselves, including worms, insects, and small crustaceans.
Breeding season is not known for x-ray fish, but some time during the year spawning occurs. The females scatter a large number of eggs throughout the water, and the males then fertilize some of those eggs. Many of them get eaten by other animals or get lost in the undergrowth in the water. The eggs which are fertilized begin developing into young fish. When these fry, or young fish, are ready to enter the water, they come out of their soft jelly eggs and join the school.
The life span of x-ray fish is two to five years. Many people keep x-ray fish as pets. They are not considered a threatened species.
Bibliography
Laidlaw, Shawn. “X-Ray Fish - Facts and Beyond.” Biology Dictionary, 28 Oct. 2020, biologydictionary.net/x-ray-fish. Accessed 16 Mar. 2024.
“X-Ray Tetra Fish Facts - Pristella Maxillaris.” A-Z Animals, 4 Apr. 2023, a-z-animals.com/animals/x-ray-tetra. Accessed 16 Mar. 2024.