Northern Victorian vets say the greatest threat posed by dead carp, affecting the Torrumbarry irrigation district after recent floods, will be from the fish finding their way into silage.
They say it's unlikely stock would eat the dead fish, although carp could pollute stock and domestic water supplies.
Carp entered the Gunbower and other creek and river systems in the area, after breeding in ideal conditions in the Gunbower Forest, following the floods.
It's believed carp have entered irrigation channels from Swan Hill to Cohuna, with flood irrigators in the area finding juvenile fish on permanent and annual pastures.
There have also been reports of juvenile carp in stock and domestic pipes.
Border Veterinary Clinic, Cohuna, vet, Dr Lachlan Fehring, said farmers had little to fear from stock eating dead carp.
"It would be very unusual circumstances in which you are going to get animals eating that kind of stuff, unless they are effectively in a paddock where there is nothing else," Dr Fehring said.
"Overall water quality is going to present a bigger issue, due to the amount of fish kills and black water events."
He said he had not heard of many people who had not had issues with water quality, in the Torrumbarry irrigation district.
"A lot of guys, who are looking to maintain hygiene and milk quality standards, have had to look at alternative water sources or change the chemical mix they use," he said.
"It's not easy to come past enough water to maintain supply for a large herd of cows, so a lot of guys have had to stick with it."
He suggested exclusion fencing, in badly affected areas, just as a precaution.
Read more:
Rochester Veterinary Practice's Keith Fletcher, also said he didn't think cattle would eat dead carp.
"The real concern would be if the carp were in paddocks that were cut for hay or silage and their bodies could be a source of botulism," he said.
"There have been a few significant outbreaks of botulism, particularly in the Cohuna area, in the past."
He said there were plenty of small carp, coming through irrigation pipes.
No silage was being made, at the moment, but lucerne was cut for hay through the summer.
Victorian Farmers Federation Water Council chair Andrew Leahy, Murrabit, said carp had been coming through his pumped irrigation system.
"You see them in the Torrumbarry channels, I had heard someone hadn't been able to put cows on the paddock, because there were too many dead fish on it," he said.
Because he was putting in maize, the fish were not such a problem.
"It's a huge problem, long term, because of the amount of carp that are growing and the degradation they will cause in the channels and rivers will be horrendous," he said.
It appeared the conditions had been right for the carp to grow, as the issue seemed to be worse than the 2011 flood.
"I can't believe they are so prevalent, compared with last time."
Subscribers have access to download our free app today from the App Store or Google Play.
Andrew Miller
I'm a general reporter with Stock & Land, with a special interest in irrigation issues. I completed my cadetship, with the Age, in 1980. Over my career, I've worked for ABC radio news (Mt Isa, Qld) and at provincial and suburban newspapers.
I'm a general reporter with Stock & Land, with a special interest in irrigation issues. I completed my cadetship, with the Age, in 1980. Over my career, I've worked for ABC radio news (Mt Isa, Qld) and at provincial and suburban newspapers.
