Fish are being reported washing up dead on beaches in Port Phillip Bay in the wake of the West Footscray factory fire and the resulting "chemical cocktail" that flushed into local waterways.
A St Kilda resident told Fairfax Media that she found dozens of dead fish on Middle Park Beach on Sunday, three days after an inferno that blanketed the surrounding suburbs in toxic smoke.
The fire has been deemed likely to be suspicious.
But Victoria Police arson and explosive investigators were yet to gain full access to site, which was still considered unsafe and continued to smoulder at the weekend.
An Environmental Protection Agency spokesman told Fairfax Media it was likely that the dead fish floated on the tide from the Stony Creek area, which flowed past the burnt factory, some 12 kilometres away.
EPA modelling shows contaminated water and other material from the West Footscray fire could reach as far as Brighton.
The spokesman said, however, that EPA officers sampled water at bayside beaches, including Brighton, St Kilda and Port Melbourne, on Sunday and nothing unusual was observed or detected.
Dead fish, eels and birds have washed up along the banks of Stony Creek and the mouth of the Yarra River near Spotswood, Newport and Williamstown since the blaze and EPA agency controller Dave Barry said officers had taken a number of specimens for analysis.
"With considerable fish deaths occurring, we’re urging people again to not eat fish caught in the creek, or 5 kilometres north or south of the outlet into the Yarra River as it could pose a risk to their health," Dr Barry said.
"We know places like the Warmies are very popular fishing spots and we want people to be able to enjoy their hobbies, but we also want them to stay safe, and unfortunately at the moment that means giving the area a miss for a few days."
Dr Barry said air-quality tests had detected benzene and toluene compounds "at levels well below the exposure guidelines", meaning they "not indicative of any significant risk to public health".
On Thursday smoke from the fire spread across the western suburbs, causing 50 schools and child care centres to be closed and alarming residents.
In a statement, the EPA said it had sampled air at three residential sites in Yarraville and Brooklyn over a 24-hour period on Friday and the results were below the level of detection for asbestos.
The agency sampled another area in West Footscray on Saturday, which also did not detect asbestos.
More than 54 staff have been involved in EPA’s response to the fire, covering monitoring, sampling and assisting emergency services agencies, since it began on Thursday morning.
The EPA said its officers would continue to monitor the bay from Williamstown through to Brighton.