The deaths of up to 60 fish on one day on Lake Burley Griffin is a mystery.
Subscribe now for unlimited access.
or signup to continue reading
The National Capital Authority and fishing expert Brian Pratt said the dead fish were the introduced species European carp and redfin.
![Experts at odds over reason for sudden fish deaths Experts at odds over reason for sudden fish deaths](/images/transform/v1/crop/frm/silverstone-ct-migration/30487c06-4cf6-4942-a4f4-0c7ab72447dd.jpg/r0_0_729_445_w1200_h678_fmax.jpg)
However, Sydney angler Harold Hill, who attended a catch-and-release fishing competition on the lake last weekend, maintained they were the introduced wild goldfish.
Mr Pratt suspected catch-and-release fishing competitions on the lake in which the carp and redfin were caught, kept alive in water and then released, might be the cause of the deaths.
The lower lake level had simply exposed more of the dead fish than usual.
He said it would be more of a concern if native species such as Murray cod or golden perch in the lake had been affected but there was no sign that was the case.
''The fish I saw appeared to have died some time ago, with no outside sign of any pathogen or injury,'' he said. However, the authority's chief executive Gary Rake was adamant neither fishing competitions nor the lake lowering had caused the deaths of the fish - although an actual cause has not been determined.
Mr Rake said the authority's contractor usually found three to five dead fish on the lake each day but over the past two weeks had found scores more, as many as 60 in one day last week.
The dead fish collected together wherever the wind blew them making for an unsightly, smelly phenomenon that was cleaned up by the contractor as soon as possible.
Mr Rake said water-quality testing had been within normal parameters for human health.
''It is quite possibly a good thing. Carp and redfin are extremely invasive pests. If it turns out to be a carp-specific disease, we'd be thrilled,'' he said.
Mr Hill said he saw the dead fish several days before the fishing competition took place and ''99 per cent of them were wild goldfish''.