The present invention relates to a method of producing an inducible animal model of stress comprising genetically modifying a non-human vertebrate to express one or more protein(s) that can be activated by light in (a) cell(s) of the hypothalamic-pituitary-adrenal axis, wherein the protein(s) that can be activated by light are capable of inducing the release of (i) corticotrophin-releasing hormone (CRH) and/or arginine-vasopressin (AVP) from neurons in the paraventricular nucleus of the rostral hypothalamus (ii) adrenocorticotropic hormone (ACTH) from corticotroph cells in the anterior pituitary and/or (iii) glucocorticoids from cells in the adrenal cortex. The present invention further relates to an animal model of stress obtained by the method of the invention and the use of said animal model for screening for a compound for preventing, ameliorating or treating stress and/or stress-associated diseases. Further, the present invention also relates to a method of screening for a compound for preventing, ameliorating and/or treating stress and/or stress-associated diseases and methods of analyzing stress behavior in fish.
