A group of ultra-Orthodox rabbis is waging a schmear campaign against a staple of the Jewish diet: lox.

Smoked salmon should no longer be considered kosher, they say, because the fish often contain parasitic worms.

But some Jewish New Yorkers aren’t taking the lox-down lightly.

“What is a bagel and cream cheese without the lox? It’s nothing,” kvetched Josh Loberfeld, 29, of Riverdale, a regular at the Mr. Bagel eatery near his Bronx home.

The ban was announced last month when a small group of rabbis decided that a tiny parasitic worm, called anisakis, rendered its host fish nonkosher.

Chevra Mehadrin, a group of hard- line Orthodox rabbis in Monsey, NY, released a list of newly forbidden fish.

But many Orthodox rabbis are blasting the group for hysterics.

“This issue has been resolved in Jewish law for hundreds of years already,” said Rabbi Moshe Elefant of the Orthodox Union.