On Friday morning it was discovered that the iconic Hochgurtel Fountain in front of the Melbourne Exhibition Centre was spewing blood-coloured water.

A Melbourne City Council spokeswoman said the dyed water was "non-toxic" and therefore thought not to pose a danger to local plants and animals.

This is lucky for the ducks who, unperturbed by the change of scenery, were photographed paddling through the crimson lake.

The fountain, drained and refilled on Friday, will be turned back on once the remaining suspected food dye residue is removed.

"Most of the red water in the lake has been pumped into sewerage," the spokeswoman said.

"It will be refilled on Monday with storm water from the Royal Exhibition Building."

There has been speculation the prank could be the work of University of Melbourne students taking part in this weekend's Prosh Week celebrations.

The incident has been reported to Victoria Police.

The suspected prank harks back to startling photos that recently emerged of the Daldykan river in far north Russia transformed into a dark shade of red.

The colour change there was later traced back to a spillage at a local metals plant.