Reports from the public about fish gasping for air have been coming in to fish habitat charity OzFish.
There are numerous reports about a fish kill in the Richmond River at Ballina, OzFish said.
The organisation has received messages and photos from locals who said thousands of fish were gasping for air, or washing up dead, following the recent cyclone and flooding.
OzFish chief executive Cassie Price said blackwater is the likely cause.
“Blackwater is caused by flooding washing organic material into waterways,” Ms Price said.
“This strips oxygen from the water as it decomposes, suffocating fish and other aquatic wildlife.”
Photos provided show dead flathead, bream, whiting, prawns and other marine life washed up on shore, and videos show dying fish gasping on the shoreline.
OzFish have also received reports of mud crabs and eels walking out of the water to escape smothering.
Ms Price said OzFish volunteers are out testing and monitoring water quality.
“The results aren’t good. Healthy water should have at least 5mg of oxygen per litre. Fish experience distress when it falls below 4mg per litre, and start to die at 2mg a litre. In Richmond River today, the dissolved oxygen levels are almost nil, sitting at 0.4 mg a litre.”
Ms Price said restoring local swamplands that border the Richmond would reduce the severity of the black water events, and fish kills.
“Healthy swamp bordering rivers acts as a sieve, or a filter, that reduces the blackwater from entering the waterway,” she said.
“Restoring the Tuckean Nature Reserve to a more natural hydrological regime would mean that much of the swamp would process the flood water, so that significantly less blackwater enters the lower Richmond after events like this.”
Read more about the Tuckean Swamp here.
Ms Price encouraged the public to record any dead fish they discover and share the information with the charity.
Record a pin drop or geo reference of your location, estimate the number of fish, take note of any key species you can identify, and take photos and videos. Send it through to info@ozfish.org.au.
OzFish is a not-for-profit member organisation that partners with fishers and locals to protect and restore waterways, counteracting decades of degradation with projects in habitat restoration, re-snagging, riverbank planting, clean-ups, fishways, shellfish reefs and educational and community capacity building programs.
More information at the OzFish website.
The information in this report was provided by OzFish.
This article appeared on indyNR.com on 16 March 2025.
