ENVIRONMENTALLY damaging koi carp fish have been spotted in Lake Gwelup and the City of Stirling is on a mission to eradicate the pests.
The ornamental fish native to Asia and Europe are popular in aquariums but can become feral when dumped in waterways, harming ecosystems and out-competing native fish.
A regular Lake Gwelup dog walker spotted the three large fish in the lake last week and snapped a photo on her phone, posting it to the Dogs of Lake Gwelup Page on Facebook.
Group members contacted Stirling Councillor Andrew Guilfoyle who alerted the City.
Stirling Parks and Reserves manager Ian Hunter said the City had confirmed the sighting and was hoping to catch the fish in the next week.
“Residents and visitors are reminded to not dump koi or any other exotic fish (or other animals) into lakes and waterways as they can cause environmental harm,” he said.
WA Fisheries Department Biosecurity Branch leader Victoria Aitken said the chances of eradicating the damaging koi carp was low because they were so common.
“Most introduced species are spread primarily by people either deliberately or accidentally,” she said.
“Aquarium or pond fish that are not native are often more aggressive than native species and can outcompete them, consuming their food and taking up their space.
“They can also spread disease, kill local species and damage natural habitats, including making the water murky and disturbed.”
Ms Aitken said the Department of Fisheries was working on raising awareness of pest fish through their Don’t Dump That Fish Campaign.
“Many Western Australian freshwater systems have been severely affected by pest species, especially in the South-West and metropolitan areas,” she said.
– Never release any aquarium life or aquarium water into marine or freshwater environments
– Aquariums and ornamental ponds should be designed and located so fish can’t escape
– If you don’t want your fish and can’t find a new home for them, or if they are sick or diseased, dispose of them humanely
– If you see an aquatic pest report it via FishWatch 24-hour hotline on 1800 815 507 or the WA Pestwatch App