Invasive goldfish the size of footballs have been known for some time now to occupy western Australia's river systems (not to mention lakes elsewhere in the world), and now comes the first evidence that they are making spawning migrations of of more than 100 miles.
RELATED: Monster Goldfish Found in Lake Tahoe
Researchers from Murdoch University studied a population of "introduced" goldfish in Vasse River and found unwelcome news about their travels.
"Our research discovered the fish displayed a significant seasonal shift in habitats during breeding season, with one fish moving over 230 kilometers [143 miles] during the year," said Stephen Beatty, co-author of a new paper on the findings, in a statement.
The researchers hope what they've learned about the fish can assist wildlife officials in efforts to control them. The colossal pests are considered invasive aquatic nightmares that upset ecosystems, introduce disease, out-compete native species, and even, potentially, decrease water quality.
"Once established, self-sustaining populations of alien freshwater fishes often thrive and can spread into new regions, which is having a fundamental ecological impact and are major drivers of the decline of aquatic fauna," said Beatty.
RELATED: 7 Pets You Should Never Release In The Wild
The fish were "introduced" to the river as either pets or aquarium-owned goldfish and then dumped, unwanted or not purchased, into local wetlands that feed into the river systems.
Once there, the fish are tough to get rid of, and they can grow to nearly 4 pounds (1.9 kg) in weight, Beatty told ABC Science.
"The goldfish population in the nutrient-rich Vasse River has existed for over two decades and has the fastest known individual growth rate of this species in the world," said Beatty.
"The results of this study will have important direct management implications," he said, "enabling more strategic development of effective control programs for the species, such as targeting migratory pathways."
Beatty and his colleagues' findings have been published in the journal Ecology of Freshwater Fish.
WATCH VIDEO: Monster Goldfish Invade Lake Tahoe