Effects of the Number of Subjects on the Dark/Light Preference of Zebrafish (Danio rerio)

Abstract

This research aims to describe the effects of a variable number of Danio rerio fish subjects, ranging from one to eight, in the light/dark box preference test. Four hundred eighty adult male short-finned phenotype zebrafish were tested in the light/dark box. There were four groups in this experiment and a different number of subjects was used in each group: the control group had only one subject, whereas the experimental groups had either two, four, or eight subjects simultaneously inside the apparatus in every session. The average occurrence (AO) of subjects in the white side of the aquarium and the first choice average (FC) were recorded. The AO revealed no difference between the control group and test groups with two and four subjects. The results for the test group with eight subjects showed significant difference when compared to the control group and from the test group with two subjects. The FC also showed no difference between the control group and test groups with two and four subjects. There was significant variation between the control and the test group with eight subjects. The results reflect a conflict between the animal's preference for dark places and the innate drive to explore new environments. Zebrafish are highly social animals, exhibiting preference for swimming in groups and other patterns of social cohesion. The reduced white avoidance behavior in the test group of eight subjects may possibly reflect the role of shoaling, which is a defensive behavior, in reducing anxiety and stress. On the other hand, the absence of difference between the control group and test groups with two and four subjects suggest that it is feasible to run the light/dark test with up to four subjects, becoming an alternative to streamline and simplify data collection and test analysis.

Effect of social isolation on anxiety-related behaviors, cortisol, and monoamines in adult zebrafish.

“…The testing tank was novel for all fish in our study, and fish responding to automated stimulus exhibited significant reduction in both turn angle and the distance to bottom. These effects are in line with previous studies that show that social stimulus can alter individual fish’s behavioral response (Faustino et al, 2017; Mansur et al, 2014). Also, these effects further highlight the complexity of multifaceted anxiety behaviors in zebrafish that have been shown to be stimulus and context dependent (Luca & Gerlai, 2012; Seguin, Shams, & Gerlai, 2016).…”

“…For example, prior social experience determines preference for certain social (Moretz, Martins, & Robison, 2007) and environmental (Schroeder, Jones, Young, & Sneddon, 2014) stimuli, while social status in a group can affect stress level and immune responses (Filby, Paull, Bartlett, Van Look, & Tyler, 2010; Forsatkar, Safari, & Boiti, 2017). Presence of conspecifics can also alter individual behavioral responses to pharmacological treatments such as alcohol (Ladu, Butail, Macrí, & Porfiri, 2014) and pentylenetetrazole (Pagnussat et al, 2013) and to adverse stimuli such as alarm substance (Faustino et al, 2017) or the strongly illuminated area of the tank in a light/dark task (Mansur, Dos Santos, Dias, Pinheiro, & Gouveia, 2014). These studies highlight the need to control the social experience of zebrafish prior to and during the experiments and to consider the social environment for the analysis and interpretation of behavioral and physiological findings.…”

Environmental and Pharmacological Manipulations Blunt the Stress Response of Zebrafish in a Similar Manner

“…Zebrafish exhibit social behavior since early stages of life 16 , preferring swimming in shoals 17 . In fact, behavioral and endocrine responses may differ according to the housing conditions and thus may be particularly influenced by group and/or isolation 18 19 20 , as well as environment complexity.…”

Embryonic exposure to fentanyl induces behavioral changes and neurotoxicity in zebrafish larvae

“…Zebrafish are highly social animals that prefer swimming in groups ( Mansur Bde et al, 2014 ). The increase of IID and NND in the shoaling test indicated that zebrafish have decreased social cohesion ( Chen et al, 2018 ).…”