Fish sampled between Bourke and Brewarrina in the Darling River during May 2008 have been diagnosed with Epizootic Ulcerative Syndrome (EUS) or 'red spot disease'. Fish sampled in different areas of the Clarence and Manning Rivers and more recently in the Wisemans Ferry area of Hawkesbury River, have been diagnosed with Epizootic Ulcerative Syndrome (EUS) or 'red spot disease'. This is caused by a fungus (Aphanomyces invadans) and shows as red lesions (sores) or deep ulcers. Secondary bacterial infections are often also associated with red spot disease.

Bony Bream from the Darling River at Bourke showing red spot disease lesion (picture R. Reece).

Lesions from red spot disease in sand whiting (picture D. Callinan)

Severely ulcerated fish should:

• not be eaten (advice from the NSW Food Authority);
• not be thrown back into the river;
• be euthanased by quickly removing the head (immersion in an ice slurry prior to decapitation should be done if possible); and
• be disposed of in land fill away from waterways.

Healthy fish with no sign of red spot disease can still be caught and consumed by recreational fishers and caught and sold by licensed commercial fishers.

Red spot disease has been previously reported in many freshwater catchments and estuaries throughout Australia, including NSW, Queensland, Western Australia and the Northern Territory. Fish species known to be susceptible to the disease include bream, mullet, whiting, dusky flathead, silver trevally, eels and catfish.

Previous outbreaks of red spot disease have been associated with acid water run-off, particularly after heavy rain following a prolonged a dry spell.

At this time, reports of red spot disease have been made in several rivers along the mid-north and north NSW coast, including the Macleay, Richmond, Manning, Clarence, Hastings and Wallamba (Wallis Lake catchment) Rivers, as well as the case further south in the Wisemans Ferry area of the Hawkesbury River.

NSW DPI will continue to monitor the occurrence of the red spot disease in the river and will collect further samples of fish as required. At this stage, there is not expected to be any significant impacts on fish populations in the river.

Please note that normal fishing rules such as bag and size limits still apply. However, compliance action will not be taken against persons who, consistent with this advice, bring ashore ulcerated fish that are below the minimum legal length for proper disposal in landfill.

For further updates, phone the NSW DPI fisheries information line on 1300 550 474.