Step Aside Scarecrows, Here Come the ‘Scarefish’

Australian researchers have designed a robot “scarefish” that mimics the natural predator of invasive Mosquito fish species, successfully scaring them off. Plus, the research team behind the robotic fish says, its newest invention not only chased away the intended target fishes, but also added further protection by negatively influencing their physiology and fertility.


According to the press release announcing the successful use of the robotic scarefish, “The invasive mosquitofish (Gambusia holbrooki) chews off the tails of freshwater fishes and tadpoles, leaving the native animals to perish while dining on other fishes’ and amphibians’ eggs.”

In hopes of finding a solution to this invasive species problem, a team of researchers from Australia, Italy and the U.S. looked to nature for inspiration. And what they found led them to develop the robotic scarefish.


“Mosquitofish is one of the 100 world’s worst invasive species,” says the study’s first author Giovanni Polverino from the University of Western Australia. “and current methods to eradicate it are too expensive and time-consuming to effectively contrast its spread.” 

In fact, said Polverino, the Mosquitofish is a “global pest,” as well as a “serious threat to many aquatic animals.”

As such, the team behind the robot scarefish looked to nature for a more effective and economical option beyond trying to kill the pesky predators one by one. This search led them to the largemouth bass, which is the mosquito fish’s natural predator. The result? A Frankenstein’s monster “that mimics the appearance and simulates the movements of the real predator.”

“We made their worst nightmare become real,” said Polverino, “a robot that scares the mosquitofish but not the other animals around it.”

Specifically, the release explains, by using its computer enhanced vision, the robot scarefish “strikes when it spots the mosquitofish approaching tadpoles of an Australian species (Litoria moorei), which is threatened by mosquitofish in the wild.”

Published in the journal Iscience, the study says the scarefish was so effective that the mosquitofish “showed fearful behaviors and experienced weight loss, changes in body shape, and a reduction in fertility, all of which impair their survival and reproduction.”

These changes in the predator’s behavior also had a positive, if not previously anticipated, influence on the previously vulnerable tadpoles, who normally form a large portion of the mosquitofish diet.

“We expected the robot to have neutral effects on the tadpoles, but that wasn’t the case,” said Polverino. “It turned out to be a positive thing for tadpoles. Once freed from the danger of having mosquitofish around, they were not scared anymore. They’re happy.”


The study’s senior author Maurizio Porfiri from New York University admits that “while successful at thwarting mosquitofish, the lab-grown robotic fish is not ready to be released into the wild.”

Therefore, to actually make their scarefish ready for a larger trial, the research team says it hopes to refine the robot in some small pools within Australia, where two types of endangered fish are currently under threat from mosquitofish. However, they note, once their scarefish is ready for a full fledged deployment, the team sees a lot of potential in implementing this type of program across the globe.

“Invasive species are a huge problem worldwide and are the second cause for the loss of biodiversity,” said Polverino. “Hopefully, our approach of using robotics to reveal the weaknesses of an incredibly successful pest will open the door to improve our biocontrol practices and combat invasive species.”

Follow and connect with author Christopher Plain on Twitter: @plain_fiction