A freshwater fish named Arnie just swam a record 530 miles, mostly upstream, Australian scientists say - CBS News
Original story by: CBS News
Last updated: Oct 27, 2025
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- Context: A Murray cod, named Arnie, has traveled an unprecedented 530 miles along a major river system, setting a potential record for the species. This remarkable journey was facilitated by floodwaters and the removal of river barriers. The fish's extensive migration provides valuable insights into the health of the Murray River ecosystem.
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- Detailed Summary:
- A Murray cod, nicknamed Arnie, has been tracked traveling 530 miles, a distance significantly exceeding previous recorded movements for the species.
- The fish was tagged in Mullaroo Creek and began its extensive journey upstream in the spring of 2022 following floods.
- The removal of river barriers, which allowed floodwaters to pass freely, is credited with enabling Arnie's long-distance movement.
- Researchers were surprised by the scale of Arnie's migration, noting that the longest previous documented travel for a Murray cod was around 100 miles.
- Understanding such movements is crucial for researchers to adapt water management strategies and protect the Murray cod's environment.
- The Murray cod is an apex predator, native to Australia, capable of living for over 48 years and growing to significant size.
- The health of Murray cod populations is considered an indicator of the overall health of the river ecosystem.
- A decade-long fish tagging project, funded by the Living Murray program and managed by the Murray-Darling Basin Authority, is collecting this data.
- Historically, Murray cod populations have declined due to commercial fishing, overfishing, river degradation, and human environmental modifications.
- The species is listed as "vulnerable" under Australia's environmental protection laws.
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