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Fish faced with stressful stimuli launch an endocrine stress response through activation of the hypothalamic-pituitary-interrenal (HPI-) axis to release cortisol into the blood. Scientifically validated biomarkers to capture systemic cortisol exposure over longer periods of time are of utmost importance to assess chronic stress in governmental, wildlife, aquaculture and scientific settings. Here we demonstrate that cortisol in scales of common carp ( Cyprinus carpio L.) is the long-sought biomarker for chronic stress. Undisturbed (CTR) and daily stressed (STRESS) carp were compared. Dexamethasone (DEX) or cortisol (CORT) fed fish served as negative and positive controls, respectively. Scale cortisol was quantified with a validated ultra-performance liquid chromatography tandem mass spectrometry method. An increase in scale cortisol content was found in STRESS and CORT but not in CTR and DEX fish. Scale cortisol content reflects its accumulation in a stressor and time dependent manner and validates the scale cortisol content as biomarker for chronic stress. Plasma analyses confirmed that (i) CTR, DEX and CORT treatments were effective, (ii) plasma cortisol of STRESS fish showed no signs of chronic HPI-axis activation, and (iii) plasma cortisol is a poor predictor for chronic stress. The expression of HPI key genes crf , pomc , and star were up-regulated in STRESS fish in the absence of a plasma cortisol response, as was the target gene of cortisol encoding subunit α1 of the Na + /K + -ATPase in gills. When lost, scales of fish regenerate fast. Regenerated scales corroborate our findings, offering (i) unsurpassed time resolution for cortisol incorporation and as such for stressful events, and (ii) the possibility to investigate stress in a well defined and controlled environment and time frame creating novel opportunities for bone physiological research. We conclude that the cortisol content in ontogenetic and regenerated scales is an innovative biomarker for chronic stress offering ample applications in science and industry.

Mycotoxins are major food contaminants affecting global food security, especially in low and middle-income countries. The European Union (EU) funded project, MycoKey, focuses on "Integrated and innovative key actions for mycotoxin management in the food and feed chains" and the right to safe food through mycotoxin management strategies and regulation, which are fundamental to minimizing the unequal access to safe and sufficient food worldwide. As part of the MycoKey project, a Mycotoxin Charter (charter.mycokey.eu) was launched to share the need for global harmonization of mycotoxin legislation and policies and to minimize human and animal exposure worldwide, with particular attention to less developed countries that lack effective legislation. This document is in response to a demand that has built through previous European Framework Projects—MycoGlobe and MycoRed—in the previous decade to control and reduce mycotoxin contamination worldwide. All suppliers, participants and beneficiaries of the food supply chain, for example, farmers, consumers, stakeholders, researchers, members of civil society and government and so forth, are invited to sign this charter and to support this initiative.