Kurzfassung:
In this thesis, a novel 20beta-HSD type 2 from zebrafish was functionally characterized and its physiological function determined. The results identify the enzyme as essential part of a novel pathway for catabolism and excretion of the stress hormone cortisol in teleost fish. The thesis contributes to the understanding of the biochemical stress reduction and provides a starting point for deeper exploration of the human glucocorticoid catabolism.