Glofish are the first genetically modified pets that are available to the public, and
it is important to look at their social behavior. The shoaling behavior of the zebrafish and
genetically modified zebrafish, yellow Glofish, was observed by calculating how much
time the fish spent near each other. This was done in four separate shoaling tests by
calculating the amount of time either a Glofish individual or zebrafish individual spent in
a 10 minute, 600 second, period when given the choice between a shoal of phenotypically
similar fish, an empty compartment, or a shoal of phenotypically different fish. The
results demonstrated that all of the four test groups showed a significant difference when
compared to the null hypothesis that the individual fish would spend 300 seconds on each
side. Therefore, both zebrafish and yellow Glofish preferred to shoal with fish that were
phenotypically similar. The overall results from the t-test and the ANOVA test proves
that zebrafish discriminate but Glofish do not. Other studies have shown that zebrafish
and red Glofish spend an equal amount of time near each other, proving that color is
important in shoaling for both zebrafish and Glofish.
Hometown: Loudon, Tenn.
Senior Study Title: “Shoaling Differences in Zebrafish, Danio Rerio, and Yellow Glofish, Genetically Altered Danio Rerio”
Advisor: Dr. Jennifer Brigati
A decade ago, when Kristen Barlow purchased her first pet fish and aquarium, she had no reason to think that they would figure prominently in her undergraduate education and have her considering animal behavior as a possible career field.
But they did.
Barlow, who graduated from Maryville College in May, majored in biology and completed a two-semester Senior Study that professors in the College’s Natural Sciences Division deemed “exemplary.” The study, titled “Shoaling Differences in Zebrafish, Danio Rerio, and Yellow Glofish, Genetically Altered Danio Rerio,” is now a part of the library’s permanent collection.
“As a biology major, I really wanted to work with live animals as opposed to looking at microscope slides,” Barlow explained. “Fish were the best choice because they were cheap to work with.
“Dr. [Drew] Crain, professor of biology, gave me the idea to do a behavioral study with Glofish because they were the first genetically modified animal available to the public. So I decided to look at the shoaling behavior between the Glofish and the fish they were modified from because shoaling [staying together] is the most common social behavior in fish.”
Dr. Jennifer Brigati, associate professor of biology and Barlow’s advisor, also liked the idea for the study and its potential to expand on research findings from prior published studies. And she was up to the challenge of guiding an advisee outside her field.
“I am a microbial geneticist, not an animal behavior expert, so the only part of this project that was familiar territory for me was working with genetically modified organisms,” Brigati said. “Kristen and I worked together to read and understand the literature, and she taught me about taking care of fish and studying their behavior!”
Barlow said designing the study that would yield statistically significant results was the most challenging task. Brigati and Crain provided some guidance; published studies gave her good ideas, as well.
She bought 12 zebrafish and 12 yellow Glofish and, for the experiments, divided a 10-gallon test tank into three separate compartments using two beakers that were placed at each end of the tank. Each beaker contained a small shoaling group (all Glofish and all zebrafish), and Barlow recorded the amount of time a fish spent on each side.
“My study was based on an experimental design of measuring the amount of time an individual fish would spend near a fish of the same type, a fish of a different type, or an empty compartment,” she explained.
She conducted approximately 60 separate trials, with each trial taking about an hour. Add to that number the hours that she spent in setting up and cleaning the tanks, the estimate that she spent in the lab grows to at least 100 hours.
It was all worth it, though, when Barlow realized that she was making discoveries about shoaling behavior that had yet to be published.
“There are now six different colors of Glofish, and my study was probably the first to use yellow Glofish,” she said. “I wanted to have something different in my study, and this difference in color definably made a difference in my conclusions.”
The findings of two tests conducted by Barlow as a part of her Senior Study indicated that zebrafish discriminate against the yellow Glofish while the Glofish do not.
“Most other studies have shown that zebrafish and red Glofish spend an equal amount of time near each other. This shows that color is important in shoaling for both zebrafish and Glofish,” she explained. “It was definitely really cool to be able to show that my study was different from other studies.”
Brigati described Barlow’s study as “suitable for publication” and recommended it for the library’s collection because it found “new and interesting data.”
“And, she was able to articulate how it fit in to the larger body of knowledge we have about the behavior of genetically modified zebrafish,” the professor continued.
More needs to be studied and understood, Barlow said.
“The [genetic] changes made to animals can impact them and the environment greatly. For example, if Glofish begin to be released into the environment, it could cause issues for other animals, she said. “I think that studies done on behavior such as mine in genetically modified organisms are important because it can show how different and possibly how dangerous these fish could be if they were introduced to the wild.”