Australia's peak animal welfare body has withdrawn its approval for a salmon farm after vision captured live fish being "inhumanely" sealed in boxes with dead ones.
Huon Aquaculture farms in Tasmania's southeast have been among those involved in mass deaths that resulted in 5500 tonnes of salmon being dumped in February.
The RSPCA suspended the company's certification on March 6 pending an investigation into a video of workers siphoning and sealing live fish in boxes.
Huon previously apologised for the incident, saying it did not reflect normal practice.
The RSPCA on Thursday announced Huon's certification for farmed Atlantic salmon had been withdrawn, labelling the conduct inhumane.
"RSPCA-approved is the leading farm animal welfare certification program in the country," RSPCA Australia CEO Richard Mussell said.
"(It) is underpinned by standards that go well above the minimum legal requirements.
"Fish, including those farmed for human consumption, are sentient beings and, like other animals, can experience pain and suffering."
RSPCA approval contains stipulations around euthanasia, including a provision fish must not be left to die in air.
The RSPCA logo will be removed from Huon products, but may remain for a short period because of practical constraints.
Huon, the only salmon company in Australia to have held RSPCA certification, said it was extremely disappointed in the decision after "a single incident of non-compliance".
"We fully acknowledge the seriousness of the incident, which was extremely distressing to us and the community," manager of stakeholder and government relations Hannah Gray said.
"For the past seven years we have been farming to a standard of animal welfare that no other Australian salmon farming company has been able to achieve.
"We will continue to farm to this standard."
Huon, which launched its own investigation, said it had put steps in place to ensure contractors upheld the company's high animal welfare standards.
The full scale of the mass deaths, caused mainly by an endemic bacterium, has yet to be made public.
More than 1000 people protested against the salmon industry on Sunday at a remote beach where chunks of farmed fish washed up.
Prime Minister Anthony Albanese copped heat for his bid to change environmental laws to safeguard salmon farms in a marginal seat on Tasmania's west coast.
Approvals for the industry in Macquarie Harbour have been under review by the federal environment minister since November 2023 after a challenge by conservationists.
The harbour is the only home of the endangered Maugean skate. Scientific advice says salmon farming is a major contributor to below-par water quality.
Legislation to amend what Labor says is a "flawed" Environment Protection and Biodiversity Conservation Act is expected to come before parliament from Tuesday.
The Coalition, who must back the legislation for it to pass the Senate, supports the salmon industry but lashed Labor for a lack of consultation.
Liberal Senator Jonno Duniam said his party wanted confirmation the legislation would guarantee ongoing salmon farming in Macquarie Harbour.
"Bipartisan support for this bill is difficult to achieve when neither industry or the opposition have seen any draft legislation," he said in a letter to the prime minister on Thursday.
It is reported changes to the act could retrospectively restrict the ability for groups to ask the environment minister to review approvals.
The Greens are against "watering down" the act and say the process is rushed and will push the skate to extinction.
