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Recent record-breaking rainfall has caused widespread flooding across Edgbaston Special Wildlife Reserve, inundating the majority of the habitat of the critically endangered Red-finned Blue-eye.
It’s a serious setback for one of Australia’s most endangered freshwater fish, but we’re not losing hope. Previous years of on ground work and research to protect Red-finned Blue-eye now provide us a practical science and evidence-based plan for recovery.
In early March, almost 300 mm of rain fell at Edgbaston Reserve in just two days, triggering flooding across the reserve and surrounding catchments. The scale of the event left Edgbaston completely inaccessible by road, so on-ground assessments are only just beginning. However, an early aerial survey by Edgbaston Reserve Manager Sam Jackson has provided critical insights into what may lie ahead.
Taking stock of the impact
Based on these assessments it appears that around 20% of Red-finned Blue-eye populations are likely still secure and free from the highly damaging and invasive Eastern Gambusia (Gambusia holbrooki) – also known as mosquitofish.
The Australian Government's Saving Native Species program funded new flood-resilient infrastructure in 2025 to protect the only wild remnant population of Red-finned Blue-eye – which contains the entire genetic diversity of the species. This appears to have performed as designed, preventing floodwaters from inundating the critically important spring.
“I’m almost certain that the former shade cloth exclusion fence would have failed catastrophically during this flood event," said Bush Heritage ecologist Dr Dean Gilligan, who leads the species recovery team. "So the work we did last year improving the protective infrastructure around this most important spring was incredibly timely.”
– Dr Dean Gilligan, Bush Heritage freshwater ecologist“This infrastructure was only installed in 2025 and has now almost undoubtedly averted a major crisis.”
Sadly, there is a very high likelihood that more than two-thirds of Red-finned Blue-eye populations have been compromised by the flood. Floodwater appears to have breached at least seven of the gambusia-free springs which will allow gambusia to invade, as well as enabling Red-finned Blue-eye to disperse beyond the previously secure habitat.
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Sample of Gambusia from an artesian spring. Photo Adam Kereszy.
– Dr Dean Gilligan, Bush Heritage Freshwater Ecologist“Red-finned Blue-eye typically disappear within 12 to 18 months of Gambusia invading, so what we do next is critical. But the good news is that we’re not starting from scratch.”
A practical science and evidence-based plan for recovery
Years of monitoring, research and on-ground trials mean there is already a clear, science-based response plan ready to deploy as soon as conditions allow. Many of these approaches have been successfully used before at Edgbaston in response to earlier Gambusia incursions, so we know we have the tools and experience to tackle this setback head on.
Key actions will include:
- Rapid surveys of all springs to confirm where Red-finned Blue-eye and Gambusia are present.
- Rescuing Red-finned Blue-eye populations from compromised springs and holding them temporarily in captivity.
- Assessing and repairing damaged fences.
- Eradicating Gambusia where feasible, before returning Red-finned Blue-eye to their home springs.
“We’ve used rescue-and-return strategies before, and we know they work,” says Dean. “In small, simple springs, we can often remove Gambusia and return Red-finned Blue-eye within a couple of weeks.”
More complex springs will likely require longer-term intervention due to the challenges of completely eradicating Gambusia. Because this process can take 12-18 months (or more), Red-finned Blue-eye populations rescued from large and complex springs need to either be held in captivity long term, or translocated to other available Gambusia-free springs.
“While these actions are more challenging and labour-intensive, they are achievable – and they’re essential because larger, more complex springs are more valuable for conservation of Red-finned Blue-eye,” said Dean.
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Red-finned Blue-eye fish. Photo Calumn Hockey.
A long road – but a hopeful one
This flooding event is a stark reminder of the growing impacts of extreme weather on already vulnerable species. But it also underscores the importance of long-term investment, preparation and persistence.
“Because we have successfully protected the wild remnant population of Red-finned Blue-eye, no matter how bad the scenario is in other springs, it can all be recovered with time, effort and adequate funding,” said Dean.
Recovery at Edgbaston will take years, not months. But with expertise, strong partnerships and continued support, there is still hope for the Red-finned Blue-eye.
The installation of flood-resilient infrastructure around the only wild remnant population of Red-finned Blue-eye in 2025 was funded by the Australian Government's Saving Native Species program.
