Rapid and reversible fish skin mucosal microbiota shift toward environmental microbial communities within a day.

Fish are constantly exposed to the surrounding environmental water, and fish skin mucosal microbiota is considered to be strongly influenced by the microbiota of the surrounding environmental water. However, the temporal dynamics of these changes, how rapidly and to what extent the fish skin microbiota becomes similar to the environmental water microbiota, remain unclear. Here, we repeatedly transferred IMPORTANCE: With respect to the response of the fish skin microbiota to changes in environmental water, high-resolution short-term temporal data would allow for the assessment and management of fish health during short periods, such as transfers between tanks. Here, we revealed that fish skin microbiota is highly plastic and rapidly and reversibly restructures itself in response to environmental changes. Two experiments reproducibly demonstrated that repeatedly transferring fish between different environments leads to the reconstruction of the skin microbiota within 1 day post-transfer, resulting in a composition more similar to that of the destination's environmental water microbiota than to that of the pre-transfer water. These results indicate that fish skin microbiota respond dynamically to the surrounding microbial environment. These findings provide a foundation for understanding host-environment microbial interactions in fish health management and aquaculture system design.