Probing aggressive motivation in a cichlid fish

Abstract

The duration of startles provides an inverse measure of motivation to resume the previous activity. Here, we use a novel method in which one convict cichlid fish ( Amatitlania nigrofasciata ) of a competing pair was startled independently of the opponent. Fish were given various opponents and the mean startle duration determined. This mean was negatively correlated with the mean use of highly escalated ‘frontal activities’ such as biting and frontal display, but not the less escalated lateral displays or tail beating. Thus the startle duration was a reliable surrogate measure of the most escalated components of aggressive interactions. That is, it provided a motivational probe for aggressiveness of individual fish. Fight motivation is often determined in terms of fight duration or physiological costs for losers, who reveal the costs they are prepared to pay. We discuss various potential advantages of the motivational probe over previous measures, particularly with respect to winners and losers and different times during the interactions.

The aggressive behavior of Nile tilapia introduced into novel environments with variation in enrichment

“…Body size is one of the most reliable indicators of a fight outcome, because strength is directly related to size (Beaugrand and Zayan, 1985;Turner and Huntingford, 1986;Frafjord, 1993;Heuts and Nijman, 1998;Chellappa et al, 1999;Jonart et al, 2007;Peixoto and Benson, 2008). Under the mutual assessment hypothesis (Arnott and Elwood, 2009b), an animal evaluates its opponent's strength from differences in RHP such as body size and avoids a fight when it is the weaker individual (Davies and Halliday, 1978;Enquist and Leimar, 1983;Manning and Dawkins, 1992;Ploger and Yasukawa, 2003;Measey et al, 2009). However, under the self-assessment hypothesis (Taylor and Elwood, 2003) the animal only has information about its own ability or state, incurring costs up to a particular RHP-related threshold at which point it gives up (e.g., Prenter et al, 2006;Stuart-Fox, 2006).…”

Environmental enrichment reduces aggression of pearl cichlid, Geophagus brasiliensis, during resident-intruder interactions

“…Thus, it is plausible to conjecture that increased territory quality might motivate more the residents so that they likely win a contest. The increased motivation might occur in terms of increased aggressiveness (Elwood et al, 1998;Arnott & Elwood, 2009). We expect that an increased number of attacks against an intruder might represent an advantage to the resident fish since this behavior may lead to a more rapid victory/ dominance in relation to a strategy of fewer attacks over a long period of time, in which greater energy loss and injury risk could occur.…”

Lateralization of lateral displays in convict cichlids

“…However, we could not record the configuration of the two fish simultaneously in the present study. In head-to-tail configuration, tailbeating by one contestant would direct water currents primarily at the opponent's head and body, and may facilitate mutual assessment [17][18][19]. Moreover, if convict cichlids align head to head, there is a significant risk of injury such as eye damage and jaw dislocation (personal observation of injuries resulting from convict cichlid fights).…”