They stir up the mud, damage aquatic plants, out-compete native fish, and generally make a mess of waterways that should be supporting cod, perch, turtles, birds, frogs and everything else that belongs there. In some river systems, carp can make up a massive share of the fish biomass, which gives you an idea of just how big the problem has become.
For years now, there has been talk of using the so-called “carp virus”, properly known as Cyprinid herpesvirus 3, or CyHV-3 as a biological control tool. It is not some magic silver bullet that will make carp vanish overnight, but the National Carp Control Plan has suggested it could reduce carp numbers by up to around 60 per cent if it is eventually approved and rolled out properly.
Recent reporting says Victorian fisheries authorities have been looking at potential Wimmera sites for a controlled carp virus trial, including old fenced water storages that were left behind after the Wimmera Mallee Pipeline changed the way water was delivered across the region. One location near Glenorchy has reportedly been among the sites discussed.
That might sound like an odd place to start, but it actually makes a fair bit of sense.
Before anyone even thinks about releasing a virus into open river systems, authorities need to understand how it behaves in real-world conditions. A fenced, disconnected storage gives researchers a much more controlled environment. You can manage access, monitor the carp, test how the virus performs, and just as importantly deal with the dead fish without having them floating down a river system and creating a clean-up nightmare.
The Victorian Fisheries Authority has previously said a field-based trial would need to be in an enclosed waterway, with the aim of testing carp mortality rates in more natural conditions. Current estimates are still based largely on modelling and laboratory work, with mortality estimates ranging from 30 to 80 per cent.
The site requirements are pretty serious too. The VFA has outlined that any preferred site would likely need to be disconnected from other waterways, have road access, water and power infrastructure, security fencing, biosecurity controls, waste treatment, disinfection facilities, and plans for dealing with dead carp either on-site or through approved disposal.In plain English: this is not a case of tipping something into a dam and hoping for the best.
And that is where these old Wimmera town storages come into the picture. If they are already fenced, isolated, and no longer part of an active town water supply, they may offer the sort of “contained test paddock” authorities are looking for. It is a very Wimmera-Mallee solution really, using old infrastructure from a previous water era to help tackle one of the biggest pest fish problems in the country.
Of course, there is still a fair way to go.
The carp virus has not been approved for broad release in Australia. The Commonwealth says more research is underway, including testing to confirm the virus only affects carp and does not pose a risk to native or non-target species. That batch of research is expected to finish in mid-2027, with agriculture ministers expected to make a decision in 2028.
So while the idea of a Wimmera trial site is interesting, it does not mean the virus is being released tomorrow. A controlled field trial would still need approvals, planning, and strict oversight.
But it does show something important: after years of talk, studies, reports and waiting, authorities are at least looking at practical ways to test this in the field.
For those of us who spend time around the Murray, the Darling, the Wimmera, or any of our inland waterways, the carp problem is not some abstract policy debate. We see it. We smell it when conditions turn bad. We see the muddy water, the damaged habitat, and the pressure on native fish.
The big question is whether the carp virus can become part of the solution, not the whole solution, but part of a bigger approach that includes native fish recovery, habitat work, carp removal, and proper river management.
If an old abandoned town storage in the Wimmera can help answer that question safely, then it might just be one of the most useful things that storage has done in years.
Because when it comes to carp, doing nothing has not exactly been a roaring success.