THE zebrafish that accompanied the Chinese astronauts on last year’s Shenzhou XVIII mission set a record for being the longest surviving fish in space, as reported by China Daily.

Sun Yonghua, the director of the China Zebrafish Resource Center at the Institute of Hydrobiology, Chinese Academy of Sciences in Wuhan, Hubei Province, highlighted that this achievement marks a significant milestone in vertebrate and aquatic plant cultivation in the space environment.

“It is the first time that zebrafish have survived for 43 days in such a closed aquatic ecosystem,” noted Sun. He mentioned that the enclosed aquarium aboard China’s Tiangong space station provided unobstructed observation opportunities.

On April 25, 2024, two male and two female zebrafish, along with hornwort aquatic plants from the institute, were transported via the Shenzhou XVIII spaceship to China’s space station. The crew returned to Earth with their samples on Nov. 4.

During their time on the station, astronauts monitored water samples, ensured the zebrafish were fed, and observed peculiar behaviors such as swimming upside down, rotating, and circling in the microgravity setting, Sun explained.

“Previously, German scientists set a record of fish living 16 days in what they called a closed equilibrated biological aquatic ecosystem, where they used swordtail fish for the experiments,” he added.

Sun highlighted that Chinese scientists are using recovered samples from closed aquatic ecosystems to analyze the effects of space conditions on the growth, development, and behavior of vertebrates.

“The Chinese space station had previously accomplished full life cycle cultivation of plants. The introduction of zebrafish into space marks the first long-term cultivation of vertebrates, establishing a scientific basis for future studies on aquatic biology and life sciences in space, and offering scientific backing for extended human missions in orbit and deeper space explorations,” Sun said.

Zebrafish, common ornamental small fish measuring 3 to 5 centimeters in body length and distinguished by their blue stripes, are considered promising model animals for research, often dubbed as “mice in the water,” according to the professor. (SD-Agencies)