Zebrafish selection strategy for the first zebrafish cultivation experiment on the Chinese space station

With the continuous advancement of space exploration activities, the development of Biological Life Support Systems (BLSS) has become crucial for supporting long-duration space missions. This paper focuses on preparation process for the multifunctional closed aquatic ecosystem (CAES) experiment based on Ceratophyllum, zebrafish, and microorganisms, conducted in the Life and Ecological Science Experiment Cabinet of the Chinese Space Station. Given the complexity and high difficulty of the experimental objectives, the selection of zebrafish individuals is critical. Prior to the experiment, the selection process considered factors such as the adaptability of zebrafish in confined spaces, social compatibility, and physiological status. A set of screening criteria was established based on preliminary experiments with 120 zebrafish, analyzing aspects like anxiety behavior, response speed, swimming posture, and shoaling behavior. Finally, based on these screening criteria, four zebrafish were selected from the pre-screened pool before the space experiment. These four zebrafish successfully survived for 43 days in the space environment and completed the predetermined scientific objectives.