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Effects of acute stress on aggression and the cortisol response in the A frican sharptooth catfish Clarias gariepinus : differences between day and night
Author(s) -
Manuel R.,
Boerrigter J. G. J.,
Cloosterman M.,
Gorissen M.,
Flik G.,
van den Bos R.,
van de Vis H.
Publication year - 2016
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/jfb.12989
Subject(s) - clarias gariepinus , photoperiodism , stressor , catfish , aggression , biology , hydrocortisone , endocrinology , medicine , psychology , developmental psychology , fish <actinopterygii> , fishery , neuroscience
African sharptooth catfish Clarias gariepinus were housed under continuous dim light (1 lx) or 12L : 12D (350–0 lx) cycles. The number of skin lesions, as indicator of aggressive acts, and plasma cortisol levels, as indicator of stress‐axis activity, were measured at baseline as well as following a stressor (given in the light or dark phase). Results showed that (1) baseline plasma cortisol levels were not different between photoperiods, (2) the number of baseline skin lesions was highest for C. gariepinus housed under continuous dim light, (3) stressor‐induced peak levels of plasma cortisol were highest in the light phase and (4) the number of skin lesions following a stressor was highest in the dark phase. The higher number of stressor‐related skin lesions in the dark (active) phase suggests increased stressor‐induced aggression while in the active phase. In addition, the data suggest that housing under continuous dim light does not result in higher stress‐axis activity, as measured by baseline levels of cortisol, but does result in more stressor‐induced aggression, as measured by the higher number of skin lesions. The latter may be related to the fact that the continuous dim light photoperiod has twice the number of dark‐phase (active) hours in which stressor‐induced aggression is stronger compared to the 12L : 12D photoperiod, which has a light phase in which stressor‐induced aggression is lower.