The Scottish Government defied concerted pleas by salmon farming multinationals to keep photos of diseased and damaged fish secret, according to internal emails.
An environmental campaigner has accused Police Scotland of acting as "private security" for a Norwegian-owned fish farming company.
At least nine million fish have been killed by diseases, botched treatments, poor handling and other problems at salmon farms around Scotland since 2016.
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 Scottish Society for the Prevention of Cruelty to Animals is facing criticism after it decided not to punish a fish farming company caught on film with lice-infested salmon.
Two fish farming companies tried to block publication of graphic images of their damaged salmon, according to emails released by the Scottish Government.
Supermarkets are selling farmed salmon from companies accused of poor animal welfare, The Ferret can reveal.
The diseases, damage and infestations suffered by hundreds of thousands of caged salmon in Scotland have been exposed by more than 300 photos released by the Scottish Government.