¿Cortisol y glucosa: Fiables indicadores de estrés de los peces?

Stress in fish has been widely studied. Cortisol and glucose are two of the most common stress indicators. In spite of the extended use of these indicators and their acceptance, some inconsistencies have been reported in the results of several experimental studies, much of them associated to undefined and uncontrolled variables which may alter the response in secretion of cortisol and glucose into the bloodstream. Most of those factors are not considered as direct stressors but have an effect on the intensity of the response which makes them a source of error. Some of those factors are related to metabolic changes in the organisms as an adaptation or acclimation mechanism; other are extrinsic to the fishes; other sources of error are caused unconsciously by the researcher during manipulation or due to inadequate control of variables, and may lead to intrinsic changes. The present paper is a contribution on the review of the most evident factors that may affect results when using cortisol and/or glucose as fish stress indicators. Some suggestions to avoid or minimize erroneous results in such investigations are also presented.