SKYFOX flew over the Neshaminy Creek Wednesday. BUCKS COUNTY, Pa. - Officials announced a "Do Not Eat" advisory for all fish species caught in the Neshaminy Creek basin in Bucks and Montgomery counties due to extremely high levels of Perfluorooctane Sulfonate (PFOS).The advisory extends to all fish throughout the Neshaminy Creek basin, including Neshaminy Creek State Park and Tyler State Park.PFOS is one of a group of perfluoroalkyl and polyfluoroalkl chemical substances (PFAS) that readily bioaccumulates in fish tissue.Pennsylvania recently adopted tiered meal advice for PFOS and has begun collecting and analyzing fish tissue samples for PFOS.