The effects of chronic stress on growth in fish: a critical appraisal

The present paper deals with the effect of abiotic environmental stressors on metabolism and growth of fish. Although generally the effect of environmental stressors on metabolism is apparent, the extrapolation to growth is not always evident. In stress research it is often difficult to establish borderline levels for chronic stress, so that increased levels of cortisol are used instead to determine when an environment becomes stressful. Because of the observed inconsistency between increased cortisol levels and depressed growth, the question can be raised as to whether cortisol is the most suitable parameter for measuring chronic stress in this context. The absence of a relationship between selected high or low cortisol response lines and growth indicates that differences between experimental animals should also be considered, particularly with respect to the innate stress response. Whether, in view of the possible existence of alternative coping styles, this automatically involves growth, is unclear.