A team of researchers from Perth’s Murdoch University found that the goldfish that get dumped into rivers and lakes are growing 10 times their original size. These fish can travel hundreds of kilometers each year through Western Australia waterways, invading the area’s native fish species.

Researchers call the goldfish as one of the worst invasive aquatic species in the world. They send sediment back into the water, which can start algae blooms. The university’s researcher, Stephen Beatty, added that goldfish also eat eggs of native fish species, which can cause population decline of other species.

The research team used acoustic receivers to study the movement patterns of a goldfish population that was introduced in the Vasse River. They observed that the fish change their habitats during breeding season, and one fish even traveled more than 230 kilometers in one year.


“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,” points out Beatty. “The results of this study will have important direct management implications, enabling more strategic development of effective control programs for the species such as targeting migratory pathways.”

The researchers explain that goldfish were once native to eastern Asia, but over time, they have spread all over the world and have ranked among the world’s most invasive aquatic species. Seventy-six species are now found in rivers in Mediterranean climate regions worldwide.

Invasive fish species can also introduce diseases, affect water quality negatively and disturb habitat conditions. Apart from these, they also compete with food resources with native fish species.

It is very difficult dealing with invasive species. However, the researchers assert that the ecological impact and deterioration of aquatic fauna will worsen over time if such problem is ignored.