A sudden outbreak of blue-green algae in the pond - which lowers oxygen levels in the pond - is believed to be behind the aquatic deaths, said Centennial Park's Horticulture Estate manager Paul Tracey.

"As the algal blooms break down, they draw down on the oxygen levels.
"There was a substantial amount of European carp lying in the shallows. "There were also hundreds of eels affected.

"A few turtles were affected - there was one dead turtle - and the rest were relocated.

"Obviously people in the park that saw it became quite concerned."