Betta Splendens: Aggression levels in males in the presence of a female stimulus
Abstract
The aggression is one of the behaviors that have been studied in the Betta splendens. In this study, the male Betta splendens behavior is affected by the presence of different stimuli such as female presence. They interact differently aggressively with the other males when the female are present. Three stimuli were tested where each of them has a different effect on different behaviors.
Introduction
Betta splendens has a normal name Siamese fighting fish and is a popular species among the freshwater aquarium fish. The genus name for this fish is derived from ikan bettah, which is a local dialect of Malay (Luna, 2013). B. splendens in most cases grow to a height of about 3 inches and it is known for its brilliant color and large fins. The natural color that is observed in B. splendens is brown and dull green. Through selective breeding, various varieties that are brilliantly colored and that have longer fin that those of the wild type have been developed. The fish belongs to the family of gourami and order Perciformes. There are more than 50 members in the Betta genus with the B. splendens being the most popular among aquarium hobbyists.
Aggression is defined as broadly as a forceful, hostile or attacking behavior of disposition. Aggression may take place either without provocation of in retaliation. The term aggression is used in the field of social sciences as well as in behavioral sciences and is used with an intention of causing harm or an action that is intended to raise the relative social dominance. The defensive or predatory behavior that exists between members of one species with members of another species is not considered to be aggression. Aggression may take physical form, communicated verbally or even non-verbally. There is a significant difference between aggression and assertiveness although these two terms are used interchangeably by most people (Akert, Aronson, & Wilson, 2010).
The aggressive behavior is one of the widely studied studies in the male category of the male Siamese fighting fish. The most aggressive varieties have been known to those that have a number of features most of which lack in species that are not aggressive. Some of these features include bright colors, long dorsal, pectoral and tail fins. The wild types have a color that is dark and uniform and their fins are shorter. These features have also been witnessed in female species (Todd, Sica, & Trahey, 2008).
The males Betta Splendens are more brightly colored than their female counterparts. These attractive features have lead to many people to explore artificial selection experiments in male species more than in female. Most of the studies explore the mutant color morphs as well as the long fins as well as tails. The variety of appearance in the Betta Splendens species has not significantly changed its courtship as well as other intraspecific displays. Both the domestic and the wild Betta Splendens usually react aggressively when another fish belonging to the same species appears.
The experiment aimed to determine the aggression levels in Betta splendens males in the presence of a female stimulus. The null hypothesis for the experiment was that the presence of a female Betta splendens did not affect the aggression level of the male species. The null hypothesis was that presence of the female Betta splendens affected the aggression level of the male species
Methods
The experiment involved four stimuli that were used to study the behavior of the Betta splendens. The behaviors of the Betta splendens were observed without the stimuli and thereafter in the presence of stimuli. The stimuli were labeled Stimulus 1, Stimuli 2, and Stimuli 3. The agonistic behaviors that were observed included open dorsal or large body, flaring of branchiostegal membrane, following other fish and facing each other laterally. The four different behaviors of the males were counted over 3 minutes. The amount of the behaviors displayed by the male Betta splendens during the male to male interaction were observed and recorded. The experiment was repeated with the introduction of the stimuli.
Results
Stimulus 1
The number of Betta splendens that showed open dorsal or large body, flaring of branchiostegal membrane, following other fish and facing each other laterally with and without stimuli 1 were as shown in Table 1 below. There were 5 Betta splendens that showed open dorsal or large body agonistic behavior without stimuli and 1 with stimuli. There were 16 Betta splendens that showed flaring of branchiostegal membrane without stimuli and 14 with stimuli. Those that showed the behavior of following others were 17without stimuli and 4 with stimuli. The Betta splendens that showed the behavior of facing each other laterally without stimuli were 10 and 4 with stimuli.
A t-test was conducted to compare the number of aggressive Betta splendens before the stimuli with the ones that showed the behaviors with stimuli. Other than the following behavior (p < 0.05), the others did not have a significant difference (p > 0.05), between the set without stimuli with the one with stimuli.
Stimulus 2
The number of Betta splendens that showed open dorsal or large body, flaring of branchiostegal membrane, following other fish and facing each other laterally with and without stimuli 2 were as shown in Table 1 below. There were 11 Betta splendens that showed open dorsal or large body agonistic behavior without stimuli and 9 with stimuli. There were 18 Betta splendens that showed flaring of branchiostegal membrane without stimuli and 12 with stimuli. Those that showed the behavior of following others were 18 without stimuli and 4 with stimuli. The Betta splendens that showed the behavior of facing each other laterally without stimuli were 17 and 10 with stimuli.
A t-test was conducted to compare the number of aggressive Betta splendens before the stimuli with the ones that showed the behaviors with stimuli. Flaring of branchiostegal membrane and the following behavior (p < 0.05), the others did not have a significant difference (p > 0.05), between the set without stimuli with the one with stimuli.
Stimulus 3
The number of Betta splendens that showed open dorsal or large body, flaring of branchiostegal membrane, following other fish and facing each other laterally with and without stimuli 3 were as shown in Table 1 below. There were 1 Betta splendens that showed open dorsal or large body agonistic behavior without stimuli and 1 with stimuli. There were 5 Betta splendens that showed flaring of branchiostegal membrane without stimuli and 1 with stimuli. Those that showed the behavior of following others were 1 without stimuli and 1 with stimuli. The Betta splendens that showed the behavior of facing each other laterally without stimuli were 2 and 0 with stimuli.
A t-test was conducted to compare the number of aggressive Betta splendens before the stimuli with the ones that showed the behaviors with stimuli. Flaring of branchiostegal membrane behavior (p < 0.05) was the only behavior that had a significant difference (p > 0.05), between the set without stimuli with the one with stimuli.
Discussion and conclusion
According to the independent T test, the data collected was statistically significant in some of the behaviors. There was a significant difference in the following other Betta splendens when stimuli 1 was included than when the there was no stimuli. All the other behaviors were not significantly different between the times when stimuli are used with when a stimulus 1 was not used. Using stimuli 2, Flaring of branchiostegal membrane and the following behavior were significantly different. This means that the behavior reduced when the stimuli was introduced. In the stimulus 3, there is significant difference in the Flaring of branchiostegal membrane behavior. For some of the behaviors the hypothesis was met while in others not. There could be errors that resulting from including different colors and this affect the aggression factor.
Reference List
Akert, R., Aronson, E., & Wilson, T. (2010). Social Psychology. Upper Saddle River: Prentice Hal.
Luna, S. M. (2013). Betta splendens Regan, 1910. Retrieved April 23, 2013, from http://www.fishbase.org/summary/Betta-splendens.html
Todd, N. E., Sica, A., & Trahey, R. (2008). Aggression, Interactions, and reference for Males in Female Siamese Fighting Fish (Betta splendens). Journal of Behavioral and Neuroscience Research, 6, 15-28.
