The Impact of Temperature Change on the Aggressive Behaviours of Siamese Fighting Fish

 The Impact of Temperature Change on the Aggressive Behaviours of Siamese Fighting Fish
Research Proposal
 
 
INTRODUCTION
            Multiple studies have demonstrated that temperature, as one of the major abiotic factors in aquatic ecosystems, has a significant effect on respiration, energy budgets, locomotion performance, growth, and behavior of aquatic ectothermic species.1 The researchers further point out that the investigation also shows that fish, as a dominant group of the ectothermic animals, characteristically experiences a broad range of temperatures across days and nights. Since the temperature has a considerable direct influence on the metabolic rates of fish, including the rest of the animals that have been categorized as ectotherms, there is a high chance for it to have large effects on their physiology and behavior.2 For instance, annual increases in temperature may result in rises in both activity and risk-taking in fish, which in turn has a correlation with elevated predation mortality.1 The existing pieces of empirical evidence on the effects of temperature on the behavioral traits have not been explored sufficiently in fish in contrast to the physiological endpoints.3,4 In this respect, most of the studies on the temperature dependence of the behavior of ectotherms, in particular fish species, have placed significant emphasis on foraging and swimming,5  which are closely linked to survival and growth indices. In the recent years, nonetheless, there has been a rapid increase in scholarly interest in the fitness consequences of temperature changes in several aquatic organisms, particularly fish.1
            Subsequently, the male Siamese fighting fish (Betta splendens) are typically known to be highly territorial and aggressive towards any intruder conspecifics.1, 6 Castro et al. explain that in aggressive interactions, the male Siamese fighting fish competitors often exhibit a ritualized order of signal behaviors, also referred to as displays.6 The researchers add that during this ritualized sequence of signal behaviors, these male competitors exchange information concerning their readiness and ability to engage in a fight. It is argued that both competitors are thought to benefit from exhibiting such ritualized sequence of signal behaviors by resolving the conflict in question without costly escalated fighting. Accordingly, these sequential typical behaviors of the male Siamese fighting fish explain the evolution of communication technique amongst the ectotherms. In particular, the male aggressively defend their territory; while doing this they utilize several highly conspicuous and stereotyped visual displays.6 It is interesting to point out that by using displays of their readiness and ability to fight to reduce the costs associated with escalated fights, it is possible for those animals that are not prone to cheat by displaying higher fighting capability than they can sustain.6 Moreover, studies that have evaluated the costs of fights between the male Siamese fighting fish have shown increased metabolic rates, the depletion of the energy reserves, and damage in ectotherms. Similarly, multiple pieces of empirical evidence have also demonstrated that there is a close correlation between temperature and metabolic rates. 7, 8, 9
                Incidentally, water temperature beyond the optimal range has been found to possess profound influence on the growth and formation of fish.7 Thus, it can be inferred that this, in turn, has an effect on the behavior of fish because the growth and formation of fish also affects how an organism acts in a particular setting.10  For example, in a study that involved seven-band grouper larvae Epinephelus septemfasciatus, it was established that there was a tendency for those animals that were reared at elevated temperatures to grow faster as opposed to the cohorts in cooler water.11 Nevertheless, Tsuji et al. observed that the survival rates of these species were highest in the optimal temperature range of 25 °C and 26 °C. A separate research has shown that the growth of brown Salmo trutta is considerably lower at fluctuating temperatures.12 Furthermore, the researchers also established that when the fluctuating water temperatures are coupled with low water levels, the Salmo trutta exhibit negative growth.  The implication of this empirical evidence is that the growth of ectotherms, including the male Siamese fighting fish, is influenced by the temperature of the surrounding water in which they inhabit. According to Flodmark et al., these findings suggest that both water temperature and stability are essential during teleost growth and development.12 Therefore, this effect on growth and, therefore, on energy requirements, also has an effect on behavior. In fact, it is worthwhile observing that with the increased metabolic rates arising from increased growth rate, organisms such as the male Siamese fighting fish are more predisposed to taking ris