The three people hospitalized Tuesday after being rescued from a large fish tank at Atlantic Sapphire's land-based salmon farming facility in Miami, Florida were not following safety protocols when they were overcome by fumes from an as-yet unidentified source, according to the top executive at the group.

Atlantic Sapphire's Miami Bluehouse facility. Photo: Atlantic Sapphire

The workers were cleaning the bottom of an empty, dry and unused growout tank, Chairman and CEO Johan Andreassen told IntraFish Wednesday afternoon, and a company investigation found the employees, who were working for a sub-contractor used by Atlantic Sapphire, did not follow what are known as "confined space safety protocols."