UK Government inspectors are investigating a Highland fish farm where video footage has exposed allegedly foul conditions.
Proposals for major expansion of the site, on Loch Shieldaig at Torridon, Wester Ross, will soon be considered by councillors.
Anti fish farm group Scottish Salmon Watch says its own video footage, taken a fortnight ago, exposes "welfare abuse, unnecessary suffering and cruelty" at a facility at Shieldaig in Wester Ross.
It appears to show farmed salmon, gasping at the surface, covered in lesions and visibly damaged.
Campaigners immediately lodged complaints with the authorities, and called for the fish to be slaughtered "to put them out of their misery".
Government inspectors have begun a formal investigation having seen the video footage submitted by the campaigners.
A small flotilla of de-lousing vessels has been onsite for several days.
The Scottish Salmon Company, which operates the facility, said it had "not had an opportunity to examine or verify the video footage and photographs", adding that there was "no evidence to suggest they are from our sites."
The statement added that "fish health and welfare is fundamental to responsible salmon farming and intrinsic in our operations".
The company is independent. It sells more than 30,000 tonnes of salmon each year to almost 30 countries.
Shieldaig Community Council and the National Trust have objected to planned expansion at the fish farm.
The trust cites a high level of mortalities which, it says, indicates a failure to manage disease effectively
Some local residents have been shocked by the video.
Janene Waudby, a potter whose home overlooks the loch, said: "This isn't a campaign against fish farming generally. The community's concern has been about the fact that it's not suitable site for further expansion and the community's concerns have been limited to that, until now.
"This footage has come out which shows some welfare issues on fish. Some photos show some serious welfare issues."
The Scottish Government confirmed that its Fish Inspectorate had received a complaint about the welfare of salmon at the site.
It has "discussed the complaint with the police, along with the UK-wide Animal and Plant Health Agency, which is investigating".
Another industry watcher wants a moratorium on fish farming in the face of Scotland-wide expansion plans.
John Robins of Animal Concern said: "They want to double the number of farms within two years. They can't cope with the number they've got. There's been extreme cruelty, terrible pollution and it's not economic. Millions, tens of millions of fish, are dying a cruel death every year."
Highland councillors are expected to consider the Shieldaig expansion proposal in August.