FREEMAN WONG starts his day just after midnight, when he heads over to the New Fulton Fish Market in the Bronx to pack his truck with whatever's fresh and attractively priced: skate, salmon, sole, shark, swordfish. Then it's off to his family's store, Aqua Best on Grand Street in Chinatown, where for the rest of the day he checks his fish to make sure their scales feel firm and their eyes shine, one of countless tasks required by the complex regulations that govern the selling of seafood.

So when he spots people selling fish outside his door without even a bag of ice in sight, he feels more than the usual resentment toward competitors.

"People are catching fish from unclean waters and selling it cheap," Mr. Wong said the other day at a busy coffeehouse next door to his bright, spacious shop. "It wreaks havoc on us."

Walk through the neighborhood's gritty southeast corner at the end of the workday and you'll see them: tanned, strong-armed men - for they are mostly men - selling striped bass or bluefish right on the street, their gleaming catches laid out on flattened cardboard boxes like so many pirated DVDs.

Sometimes, instead of fish, they set out plastic bins filled with slick fists of conch meat, or wood-slat buckets teeming with periwinkles.

Occasionally a horseshoe crab, turned on its back, helplessly flails at passers-by from the pavement.

While it's against the law to sell raw seafood on the sidewalk, for the obvious reasons involving health and sanitation, these vendors do a steady business by charging 20 or 30 percent less than Chinatown's low-priced fish markets.