Comparison of the activity and aggressive levels of two varieties of Betta splendens: halfmoon double tail and veiltail
Introduction
B. splendens, Betta fish or Siamese fighting fish are found in Thailand, Cambodia and Vietnam and live in slow-moving and stagnant water like streams, ponds, and rice paddies (Chailertri et al 2014, Strugeon 2001). B. splendens have a special organ above their gills, the labyrinth, that help them breathe. The labyrinth acts as an internal air reservoir which enables them to obtain oxygen right into their blood stream (Monvises et al. 2009). Wild B. splendens are not known to be colorful, in fact they are a duller color of brown or red. Both wild and bred B. splendens use their coloration to attract their mates (Strugeon 2001). When it comes time to mate, male B. splendens create bubble nests where they store their fertilized eggs. After selecting a mate, female Betta fish lay their eggs which the male Betta fish capture with their mouths and take to their nests. The male Betta fish shows aggression to defend and protect the eggs (Jaroensutasinee and Jaroensutasinee 2001, Todd et al. 2008). Male B. splendens are known to show high levels of aggression towards each other to not only protect eggs or offspring, but to also claim territory (Herbs et al. 2002). B. splendens may display their aggression through fin flare, biting, broadside display and more.
Although we do not exactly know why varied species of B. splendens show different activity level and aggression, genetics may play an important role in aggressive behaviors. An experiment conducted on deer mice (Peromyscus maniculatus sonoriensis) showed that indirect genetic effect (IGE) play a significant role in setting the evolutionary potential for aggression (Wilson et al. 2009). Out of the five traits they studied, there was support for the presence of IGEs in three of the traits. They estimated that correlations between direct and indirect genetic effects were high. This means that aggression in the mice was a result of both evolutionary and a social environment reasons. (Wilson et al. 2009). In conclusion, the results showed that IGEs play a significant role in setting the evolutionary potential for aggression in this experimental system. The objective of this experiment was to compare and observe the activity and aggression levels of two varieties of B. splendens at Hope College Holland, Michigan. Therefore, we the evaluated the two varaities of B. splendens for differences in activity and aggression level.
Methods
Activity and aggression levels of male halfmoon double tail and veiltail Betta splendens were analyzed at Hope College, Holland Michigan on November 14, 2017 and November 16, 2017 by Biology 107 students. The Betta splendens were purchased a minimum of 3 days prior to the experiment from a local pet store in Holland Michigan. They were placed inside a 20-gallon tank that was divided into two equal sections and one fish was placed in each section. On each lab table two 20-gallon tanks were placed with a total number of four Betta splendens: two halfmoon double tail and two veiltail. The fish were fed 2-3 pellets of Aquein Betta Food daily. To enhance the environment for the fish, glass rocks and plastic plants were placed inside the tanks. The water temperature was ambient, and the room temperature was 22° C. Half of the water in the tank was replaced each week. The fish were exposed to 10 hours of light and 14 hours of darkness each day (Muilenburg et al. 2016).
Each fish’s activity and aggression were measured through line crosses, latency, broadside display, fin display, biting, and opercula display. The lab students were divided into groups of four and each person in a group was assigned a role. Each student timed and observed the activity and aggression as described in Muilenburg et al. 2016.
All student collected data on mean line crosses, latency, broadside display, fin display, biting, and opercula display was compiled and analyzed using an independent samples t-test in SPSS 23 in which a p-value of 0.05 or less would indicate statistical significance. The independent variable for line crosses was the variety of Betta splendens and the dependent variable was the number of mean line crosses. The independent variable for latency was the variety of Betta splendens and the dependent variable was the amount of time the fish did not display any aggressive behavior. The independent variable for broadside display was the variety of Betta splendens and the dependent variable was amount of time spent showing broadside display (>1 inch). The independent variable for fin display was the variety of Betta splendens and the dependent variable was the total amount of time the fish displays its fin. The independent variable for biting was the variety of Betta splendens and the dependent variable was the amount of times the fish bit during the five minutes after aggression. The independent variable for opercula display was the variety of Betta splendens and the dependent variable was the amount of time the opercula was displayed in seconds.
Results
The two varieties of Betta splendens, veiltail and halfmoon double tail had statistically significant different activity levels. With a mean of 87.621 veiltail had greater line crosses compared to halfmoon double tail that had a mean of 54. (t=2.392 w/ df = 54; p < 0.05). The two varieties of Betta splendens, veiltail and halfmoon double tail had statistically significant different latency. Veiltail had a lesser latency level with a mean of 31.2124 compared to halfmoon double tail that had a mean of 121.0344. (t=2.225 w/ df = 54; p < 0.05). The two varieties of Betta splendens veiltail and halfmoon double tail had statistically significant different mean broadside display. Veiltail showed greater broadside display with a mean of 138.407 than halfmoon double tail that had a mean of 78.3937. (t=3.142 w/ df = 54; p < 0.05). The two varieties of Betta splendens veiltail and halfmoon double tail had statistically significant different mean fin display. Veiltail had a greater fin display with a mean of 219.0915 compared to halfmoon double tail that had a mean of 175.9224. (t=3.206 w/ df = 33; p < 0.05). The two varieties of Betta splendens veiltail and halfmoon double tail had statistically significant different mean bitting. Veiltail bit more with a mean of 4.382 compared to halfmoon double tail that had a mean of 2.088. (t=3.119 w/ df = 33; p < 0.05). The two varieties of Betta splendens veiltail and halfmoon double tail had statistically significant different mean opercula display. Veiltail showed greater opercula display with a mean of 178.56234 compared to halfmoon double tail that had a mean of 113.92678. (t=2.521 w/ df = 33; p < 0.05).
Discussion
The results show that veiltail Betta splendens had significantly higher activity levels and aggression. This supported our working hypothesis that there will be significant difference in aggression and activity levels of Betta splendens. Across all six behaviors of aggression: line crosses, latency, broadside display, fin display, biting, and opercula display (Fig 1- 6) veiltail Betta splendens showed higher levels of activity. The results were very consistent unlike results from previous years.
The gene for the veiltail Betta splendens are known to be dominate while the gene for the halfmoon double tail Betta splendens are recessive (Baumgarten 2001). This tells us that the veiltail Betta splendens are the dominant species over the halfmoon double tail. A study was conducted on Zebrafish to find the neurophysiological basis of aggression in fish. In this experiment gene expression profiling was used to better understand aggression. It was found through the experiment that aggression was more prominent in dominant fish compared to the subordinate zebrafish (Filby et al. 2010). This suggests that veiltail Betta splendens showed more aggressive behavior because it had a dominant trait. Another study conducted recorded that female Siamese fighting fish, B. splendens, mates the winner of male-male aggressive interactions (Herbs et al. 2002). The sight of the fish’s own reflection will stimulate aggressive behaviors as the dominant organism will have greater access to food, space and mates (Clotfelter & Paolino, 2003).
Although it was not complex to observe the aggression and activity levels of Betta splendens it was quite difficult to understand why varied species of Betta splendens showed different levels of aggression and activity levels. Our research contributes to our understanding of how genetics may play a role in our behaviors. We now know that it is not only the external factors, but also internal factors like genetics that affect how fish behave. Future research should focus on how external factors like chemicals that may end up in ponds, streams and rice paddies affect the behavior of Betta splendens.
Literature Cited
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Tables and Figures
Fig 1: Data analyzed using an independent samples t-test in SPSS 23 showed that the mean number of line crosses per 5 min in B. splendens veiltail (N = 29) was greater than B. splendens halfmoon double tail (N = 27) (t=2.392 w/ df = 54; p < 0.05)
Fig 2: Data analyzed using an independent samples t-test in SPSS 23 showed that the mean latency per 5 min in B. splendens veiltail (N = 29) was less than B. splendens halfmoon double tail (N = 27) (t=2.225 w/ df = 54; p < 0.05)
Fig 3: Data analyzed using an independent samples t-test in SPSS 23 showed that the mean broadside in B. splendens veiltail (N = 29) was less than B. splendens halfmoon double tail (N = 27) (t=3.142 w/ df = 54; p < 0.05)
Fig 4: Data analyzed using a paired samples t-test in SPSS 23 showed that the mean fin display in B. splendens veiltail (N = 34) was greater than B. splendens halfmoon double tail (N = 34) on November 14, 2017 and November 16, 2017 at Hope College, Holland Michigan. (t=3.206 w/ df = 33; p < 0.05)
Fig 5: Data analyzed using a paired samples t-test in SPSS 23 showed that the mean biting in B. splendens veiltail (N = 34) was greater than B. splendens halfmoon double tail (N=34) on November 14, 2017 and November 16, 2017 at Hope College, Holland Michigan. (t=3.119 w/ df = 33; p < 0.05)
Fig 6: Data analyzed using an paired samples t-test in SPSS 23 showed that the mean fin display in B. splendens veiltail (N = 29) was greater than B. splendens halfmoon double tail (N = 27) on November 14, 2017 and November 16, 2017 at Hope College, Holland Michigan. (t=2.521 w/ df = 33; p < 0.05)
