Fish and Game Otago had been informed by the Ministry of Agriculture and Forestry that the hatchery trout found to be infected with the aeromonas bacteria did not have the "typical" strain, Otago Fish and Game chief executive Niall Watson said.
"The `typical' version of the bacteria is of most concern to hatchery and fish-rearing facilities so it's encouraging that this has been ruled out."
Further testing was needed to prove what variant of the bacteria it had, he said.
"We understand that if further tests return a positive for the 'atypical' strain, then this is less virulent in trout."
They would consider the implications of Maf's results over the next few days and review the situation at the Macraes hatchery in a few weeks before deciding whether to recommence releases from the hatchery.
The stock held there all appeared to be in a healthy condition and they were continuing to monitor the situation closely.
"Since the discovery of the disease, we've enforced strict hygiene controls on-site and have a self-imposed restriction on further fish releases."
There have been no reports of infected trout from waterways where releases were made before the discovery of the infected hatchery fish, he said.
