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Article History

Received: 19 November 2025

Accepted: 2 April 2026

First Online: 21 April 2026

Declarations

:

: All fish were handled and euthanized following protocols approved by the Smithsonian Tropical Research Institute’s Institutional Animal Care and Use Committee (IACUC; SI-22047). We used rapid chilling (hypothermic shock) to euthanize fish. This was done by rapidly transferring fish after capture into individual labelled bags—allowing direct contact with the chilled water but not the ice—and placing them in an ice slurry in a large cooler on the boat. This method was deemed appropriate as we are working with relatively small, tropical fish that are acclimated to temperatures around 29-31ºC. We also wanted to avoid the use of chemical agents, as these could potentially impact our downstream microbiome analyses. Fish were kept in the cooler for a minimum of 20 min, then assessed to confirm lack of movement, and kept on ice until we returned to the lab and began dissections.

: Not applicable.

: The authors declare no competing interests.