Assessing Chronodisruption Distress in Goldfish: The Importance of Multimodal Approaches

Abstract

Chronodisruption caused by factors such as light at night and mistimed meals has been linked to numerous physiological alterations in vertebrates and may be an anxiogenic factor affecting welfare. This study aims to investigate whether chronodisruption causes measurable changes in the anxiety responses of goldfish under two conditions: randomly scheduled feeding (RF) and continuous light (LL). Anxiety-like behavior was assessed in the open field with object approach and black/white preference tests, which had been validated using diazepam. An increased thigmotaxis response and decreased object exploration under both chronodisruption protocols indicated anxiety states. Furthermore, locomotor activity was increased in LL fish. The black/white preference test discriminated anxiolysis induced by diazepam but was unable to detect anxiety caused by chronodisruption. Plasma cortisol increased in both RF and LL fish throughout the experiment, confirming that both conditions caused stress. The LL fish also showed an apparently desensitized hypothalamus–pituitary–interrenal HPI axis, with a decrease in pomc and crf expression. Individual analysis found no correlation between anxiety-like behavior and stress axis activation nor between scototaxis and thigmotaxis responses. However, individual differences in sensitivity to each test were detected. Altogether, these results highlight circadian disruption as a stressor for fish and endorse a multiple variable approach for reliably assessing animal discomfort.

Age-related alterations in the behavioral response to a novel environment in the African turquoise killifish (Nothobranchius furzeri)

“…In the open field test, we observed the same thigmotaxis behavior as found in other fish species ( Stewart et al, 2012 ; Ahmad and Richardson, 2013 ; Lucon-Xiccato et al, 2022 ; Saiz et al, 2023 ). This means that killifish avoid the center zone and prefer swimming close to the edges.…”

“…The novel tank diving test typically studies exploration, diving, and immobility/freezing behavior ( Blaser and Rosemberg, 2012 ; DePasquale et al, 2022 ). Different teleost species display different behaviors in these types of behavioral tests ( Egan et al, 2009 ; Cachat et al, 2010 ; Matsunaga and Watanabe, 2010 ; Godwin et al, 2012 ; Audira et al, 2021 ; DePasquale et al, 2022 ; Lucon-Xiccato et al, 2022 ; Saiz et al, 2023 ). In this study, we, therefore, tested the new aging model organism N. furzeri in the open field test and the novel tank diving test over its adult lifespan to set a baseline for future behavior experiments.…”