Shellfish caught in the Hobsons Bay area is off the menu due to an algal bloom outbreak.
The Department of Sustainability and Environment has issued a warning to not eat shellfish taken from the Williamstown and Newport areas.
The algae is not visible to the eye, and it not dangerous to swimmers. It has not affected commercial shellfish farms.
DSE Port Phillip Regional Director, Rodney Warren, said a routine sample has found high levels of the naturally occurring toxic algae Alexandrium catenella, which can accumulate in shellfish like mussels, pipis, oysters and scallops and potentially be toxic to humans.
"It is still safe to eat any shellfish brought from shops or supplied by commercial fisheries,'' he said.
"We are undertaking further sampling today to determine if the bloom has dispersed or moved on following the currents of the bay.
"The Department of Health has advised us it is still safe to swim in the area but people should not eat shellfish collected from areas north of Newport. The Department of Health has also advised that anyone who is feeling unwell after eating shellfish collected from the area should visit their doctor as a precaution''
The algae occurs naturally at low, non-toxic levels in the bay throughout the year but has multiplied in the recent warm, still weather conditions.