Nearly 200 fish farms are allowed to use a carcinogenic chemical called formaldehyde which is used to embalm corpses.
Scottish Government inspectors have launched an investigation into video evidence of alleged animal cruelty at a salmon farm on the north west coast.
The multinational salmon farming industry has been pushing behind the scenes for environmental limits on a toxic pesticide to be 100 times weaker than government regulators recommend.
At least nine million fish have been killed by diseases, botched treatments, poor handling and other problems at salmon farms around Scotland since 2016.
A leading Scottish salmon farming company has stopped branding its business as “sustainable”, according to the UK advertising watchdog.
The £2 billion salmon farming industry marketed around the world as Scottish is virtually all owned by investors in Norway, Switzerland, Cyprus, Canada and other countries.
Government officials raised concerns over the import to Scotland of salmon eggs from a Norwegian company called AquaGen after the outbreak of a deadly virus.
The use of cleaner fish on Scottish salmon farms as a treatment for sea lice should be suspended due to serious welfare issues, according to a report by animal rights campaigners.
Scotland's fish farming industry must bow to tougher environmental regulation if wants to expand, a committee of MSPs has concluded.