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Nets deployed after suspected koi sightings in Adelaide’s River Torrens

More than a dozen suspected koi were seen near Hackney, ABC News reported. Green Adelaide is trying to catch fish upstream and urging residents not to release unwanted pets into the river.

NewsJaws DeskEditorial desk

Published 26 Oct 2026, 22:34 GMT2 min read

A view of the River Torrens in Adelaide. — File photograph of the River Torrens in Adelaide, taken in September 2026. Yu Chu Chin, “River Torrens in Adelaide, September 2026 (028A1349).jpg” (resized and converted to WebP). CC BY-SA 4.0.Image source Image licence: CC BY-SA 4.0

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More than a dozen suspected koi have been seen in Adelaide’s River Torrens near Hackney, with a smaller number sighted upstream at Dernancourt, ABC News reported on Tuesday, 27 October. Nets are being used at Dernancourt to try to catch the fish, while residents are being urged not to release unwanted pet fish into the waterway.

The group at Hackney appeared between St Peters Weir and Hackney Bridge. Stuart Collard of Green Adelaide, which manages the river environment, told ABC News that seeing so many koi there was unusual. He said the organisation suspected members of the public had released them; how the fish arrived has not been established.

Why Green Adelaide wants the fish caught early

Collard said koi compete with native fish for food. As bottom feeders, they also stir up sediment and disturb plants on the riverbed, affecting their growth. He said early action matters because invasive fish populations can expand and occupy more of the river. ABC News did not report whether the nets had caught any fish.

Green Adelaide identifies introduced fish as one of several threats to native fish in the River Torrens, alongside pollution and changes to habitat caused by water management. It monitors native fish in autumn or spring to assess the effects of work to improve the river.

Goldfish are already a persistent presence. Collard told ABC News that Green Adelaide regularly catches them during river surveys and understands that a self-sustaining population lives there. James Johnston of the Invasive Species Council said the suspected koi sightings were disappointing given efforts to help native fish, rakali and other species thrive.

Rules on releasing pet fish in South Australia

Keeping koi in South Australia requires a permit from the Minister for Primary Industries, according to ABC News. Releasing koi, goldfish or other non-native fish into the state’s rivers is illegal and can draw a fine of up to $120,000. Collard urged people not to dump unwanted fish in the Torrens.

The river is also the focus of a separate plan to return platypus. South Australia’s government announced an additional $4 million for that effort in August, ABC News reported. Platypus were last recorded in the waterway in the 1880s; Collard said it was getting close to being able to support a population again.