Chinese researchers sent a bunch of zebrafish to space and now they’re swimming weirdly!

Aboard China’s Tiangong space station, four zebrafish 'aquanauts' are thriving in their out-of-this-world home. Experts from the Chinese Academy of Sciences (CAS) report that these finned pioneers are in top shape after more than three weeks in orbit.

Launched on April 25 along with three astronauts aboard the Shenzhou-18 spacecraft, the zebrafish and four grams of goldfish algae embarked on a historic mission to establish a self-cycling aquatic ecosystem in microgravity — a first for vertebrate-raising experiments in space, as reported by Xinhua.

"The astronauts have managed to collect water samples twice and have replaced the fish food box once," revealed Zheng Weibo, a researcher at the Shanghai Institute of Technical Physics of the CAS. "They found that the zebrafish were showing directional behaviour anomalies, such as inverted swimming and rotary movement, in the microgravity environment on Tiangong."
This ambitious project, orbiting about 400 km above Earth, aims to study the impact of the space environment on the growth, development, and behaviour of vertebrates, as well as the material cycle of confined ecosystems in space, using samples like water and fish eggs.

Zebrafish, with their genetic similarity to humans, are considered model animals for research on many human diseases, according to Wang Gaohong from the CAS Institute of Hydrobiology. "Meanwhile, like astronauts, zebrafish need to pass through rounds of selection to become 'aquanauts,'" Wang added.

This closed-loop system, where algae and fish coexist and sustain each other, could inform the design of life support systems for future space habitats. The successful establishment of this self-sustaining aquatic habitat marks a significant breakthrough in the field of raising vertebrates in space.

By observing the zebrafish and analysing the samples collected, scientists hope to gain valuable insights into the challenges of maintaining life support systems for extended space missions and potential future space settlements. The experiment also holds promise for advancing our understanding of human health and disease processes, as the zebrafish's responses to the space environment could shed light on the effects of microgravity and radiation on biological systems.