The Ministry of Agriculture and Forestry (MAF) today confirms that a single, juvenile trout from the Taieri River in Otago has tested positive for the same bacterial disease that is causing illness and death in kanakana (lamprey) in Southland.

MAF Biosecurity Response Manager Glen Neal says the Ministry is working to determine the exact strain of the new to New Zealand Aeromonas bacterium that is causing the fish illness. Results are expected to take some time - due to complexities around the laboratory methods and the bacterium involved.

"It is notoriously difficult to culture the bacterium," says Mr Neal.

"The detection of a strain of this bacteria in a trout is, unfortunately, not unexpected. This has not been found in any other species in New Zealand to date. We know, however, that this bug can affect a range of fish including lamprey, trout, eel, salmon, whitebait and kokopu."

The new detection was a fish from a trout hatchery where fish are raised to stock waterways for recreational fishing. It is so far the only affected fish found amongst thousands in the facility. MAF is continuing to work closely with the hatchery management following the find.

The Aeromonas bacterium involved does not pose a direct risk to human health. MAF does, however, recommend that people do not eat any fish that appear unusual or unhealthy.

Fish with the bacterial illness are likely to have red and/or swollen fins and red and/or swollen marks that look like bruises or blood clots.

Mr Neal says members of the public can help MAF in its investigations by reporting sick or dead fish to its pest and disease hotline 0800 80 99 66.

"We are also keen to remind waterway users of the importance of checking, cleaning and drying their equipment and clothing when moving between waterways."