Carbajal, A., Soler, P., Tallo-Parra, O. et al. 2019. Towards non-invasive methods in measuring fish welfare: The measurement of cortisol concentrations in fish skin mucus as a biomarker of habitat quality. Animals 9(11), 939.
Cortisol levels in fish skin mucus have shown to be good stress indicators in farm fish exposed to different stressors. Its applicability in free-ranging animals subject to long-term environmental stressors though remains to be explored...