Initial investigations indicate a gas incident at Tassal's Strathblane facility near Dover on Sunday which hospitalised 20 people was due to forklifts being used in a building.
Barry Bones from the Tasmania Fire Service has told Seven the symptoms were indicative of carbon monoxide poisoning.
"There were a few patients that presented with some respiratory illness, difficulty in breathing, nausea, which is a classic sign of people that have been exposed to that gas," he said.
Hobart Private Hospital made its ED available to help the Royal cope with the influx.
Professor Anthony Lawler, Chief Medical Officer, Department of Health, provided an update on Sunday evening.
"All patients have been assessed and are stable," he said.
"At this stage, three patients will be admitted overnight, while others will be discharged for further treatment in the next 24 hours."