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Article History

Received: 18 February 2025

Revised: 25 May 2025

Accepted: 27 May 2025

First Online: 12 June 2025

Declarations

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: All animal handling and experiments were conducted in strict accordance with the ethical requirements and animal care recommendations of Chongqing Key Laboratory of Conservation and Utilization of Freshwater Fishes, China (Permit No. Fu2020112302), as well as the environmental and housing facility requirements for laboratory animals in China (GB/T14925-2001). Additionally, all experiments adhered to the local animal welfare laws (i.e., the measures of the Chongqing municipality for the administration of experimental animals) in Chongqing city, China. To minimize stress in the fish, we conducted multiple trials to assess their phenotypic traits. The fish were gently transferred from holding tanks to measuring arenas (such as mazes, respirometer chambers, and personality tanks) using a small plastic cup without any exposure to air. Unnecessary chasing or capturing of the fish during handling was avoided. During acclimation, we maintained a low fish density of 0.4 individuals per liter in the holding tanks while monitoring and controlling water temperature and dissolved oxygen levels to simulate natural environmental conditions with a photoperiod of 14 L:10D. Plastic green plants were also provided as shelters in the holding tanks to meet animal welfare requirements. The fish were fed mixed bloodworms ad libitum once daily. At the end of the experiments, all fish were euthanized by administering an overdose of buffered tricaine methane sulphonate (MS-222, 100 mg L−1) in order to measure their brain sizes.

: The authors declare that they have no conflicts of interest.