This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: In the world of aquatic life, the Mozambique tilapia (Oreochromis mossambicus) is remarkably tolerant of saltwater, surviving in habitats ranging from fresh water to hypersaline ponds three times saltier than the ocean. Researchers at the University of Hawaiʻi at Mānoa's College of Tropical Agriculture and Human Resilience (CTAHR) have identified one of the molecular mechanisms underlying this feat.
The study, published in General and Comparative Endocrinology, was led by Andre Seale, a researcher and professor in CTAHR's Department of Human Nutrition, Food and Animal Sciences, alongside UH student researchers. By gradually increasing the salinity of tank water with artificial sea salt, the team discovered how the fish survive under extreme salt stress. Several fish species, including tilapia, need the hormone prolactin to prevent excessive water uptake and ion loss in fresh water and reduce its activity when entering saltwater.
However, in extreme hypersalinity, prolactin signaling continues to be suppressed, while the types of prolactin genes being expressed continue to shift. This allows the fish to fine-tune their ability to regulate salt and water balance even during transitions into salty environments. "This salinity acclimation capacity is gradual, and even this species will fail to survive a direct transfer from fresh water to seawater.
Understanding the rate and limits of how these fish tolerate higher salinities also helps improve production traits, including growth, feed efficiency and nutritional value," said Seale. Tilapia is a staple of global aquaculture and local Hawaiian aquaponics. Understanding the mechanisms underlying salt tolerance enables farming in brackish water, preserving fresh water for agriculture and drinking.
It also allows for the investigation of how saltwater may affect the nutritional quality of the fish. By enabling tilapia farming in salty water, this research could play a role in boosting fish production and quality in regions with limited freshwater supply. Seale et al, Prolactin signaling in the highly osmotolerant Mozambique tilapia, Oreochromis mossambicus, General and Comparative Endocrinology (2026).
DOI: 10.1016/j.ygcen.2026.114902 Journal information: General and Comparative Endocrinology Provided by University of Hawaii at Manoa Swati Mestri holds a bachelor's degree in Electronics Engineering and has worked as a content editor since 2019. She has experience editing research documents across technology, health care, and materials science, and has a particular interest in technology and space. Full profile → Master's in physics with research experience.
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