Aquarium species established in ocean waters
13 non-native marine species have established themselves in California waters after being flushed down toilets, scientists say.
A report from the University of California, Davis has found that over 11 million non-native ornamental marine individuals - including tropical fish, seaweed and snails - are being imported annually through the ports of San Francisco and Los Angeles. These represent at least 102 different species and come primarily from Indonesia and the Phillipenes. 13 of these species have established themselves in California marine waters, presumably after being released from aquariums.
Whilst this is a relatively low number, the report has warned that 69% of the introduced species successfully established themselves in California, indicating a potential threat to marine eco-systems. Non-native, invasive species could out-compete native species for habitat and food.
The aquarium trade, according to the report, represents a highly popular home hobby second only to photography. It is a $1 billion a year industry that has introduced some of the worst invasive species in the world, says Susan Williams, lead author of the study. These include the seaweed Caulerpa, known as "the killer algae" that infected two lagoons in Southern California in 2000, costing over $6 million to eradicate.
The lionfish is another of the species highlighted as in the report as being of particular concern. This species is highly predatory and regularly enters the state's ports through the aquarium trade. Though the lionfish has not been reported in California waters, they are able to withstand cooler temperatures and could be established as far north as San Francisco bay and further, scientists say.
Whilst this report is one of six exploring different ways invasive species can enter California Waters, Williams says it is easier to prevent unwanted aquarium species entering the waters, through methods such as public education. She recommends anyone who no longer wants an aquarium species should contact the vendor or the California Department of Fish and Wildlife.
The Veterinary Medicines Directorate (VMD) is inviting applications from veterinary students to attend a one-week extramural studies (EMS) placement in July 2026.
