Department of Fisheries and Aquaculture

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Browsing Department of Fisheries and Aquaculture by Author "Ariyomo, Tolulope Omolayo"

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    Effects of sex and size on boldness and aggression in the zebrafish and the guppy
    (2020) Ariyomo, Tolulope Omolayo
    In this study, we tested the differences in boldness and aggression in relation to sex and size in three strains of zebrafish (London Wild Type (LWT), Tupfel Long fin (TL) and Nacre) and a population of guppies. The objective of this study was to determine the influence of sex and size on boldness and aggressiveness in the zebrafish and the guppies. The open field test was used to test for boldness while the mirror test was used to test for aggression. Twenty five males and 25 females of each of the zebrafish strains (LWT, TL and Nacre) and 25 male and 25 female guppies were used in this study. Our results showed that boldness and aggression varied between individuals and that these traits were associated with sex in some populations and not all. The LWT males and the Nacre males were bolder than the females of the same strain (p = 0.001 and p<0.001 respectively) but there was no significant difference in boldness between the TL males and females (p = 0.980). There was no significant difference between LWT males and females and TL males and females (p = 0.999 and p = 0.885) in aggression. However, Nacre males were significantly more aggressive than Nacre females (p<0.001). In the guppies, the males were bolder than the females (p <0.001) but there was no significant difference in aggression between the male guppies and the female guppies (p = 0.062). Our results showed that boldness and aggression varied between individuals and that these traits were associated with size in some populations and not all. In the TL females, smaller females were bolder than larger females (p = 0.012). However, size did not have any influence on boldness in the Nacre females, the Nacre males, the LWT females, the LWT males and the TL males (p = 0.381, p = 0.267, p = 0.183, p = 0.249 and p = 0.229 respectively). In the TL females, smaller females were more aggressive than larger females (p = 0.026) but there was no correlation between length and aggression in the males and females of any of the other strains of zebrafish (p>0.05). Furthermore, in the guppies, size did not have any effect on boldness or aggression (p = 0.089 and p = 0.660 respectively). The variation in the effect of sex and size on boldness and aggression reported here may be due to factors, such as metabolic requirements, hormonal differences, and differences in the reproductive roles of both sexes of the population tested.