SICK redfin caught at Burrendong Dam in April may have been affected by parasites and bacteria but tests were inconclusive as to the exact nature of the cause of the marks.
A number of anglers at the dam have caught redfin that were covered in red blotches, prompting concerns.
Samples were provided to the NSW Department of Primary Industries (DPI) by recreational fishermen and the aquatic biosecurity team had laboratory testing carried out but it was inconclusive.
It has been suggested the cause could be environmental but without further testing, the exact cause won’t be found.
The NSW DPI has requested anyone who catches a redfin exhibiting red blotches to provide it for further investigation.
It has also advised people not eat fish that have severe ulcers.