The fish secret they don’t want you to know about (they=brunch places)

Walking the short length of Gem Street, in an industrial stretch by the Williamsburg/Greenpoint border, you’d never guess you were homing in on a gastronomic polestar. But the squat brick building at No. 30 is home to Acme Smoked Fish, where every year millions of pounds of whitefish, trout and especially salmon are kissed by wood smoke and salt and sent out to purveyors including Russ and Daughters, Fairway, Zabar’s and Citarella. Call it Fort Lox.

What’s in it for you? Two words: Fish Fridays.

That’s when the salmon stronghold sells direct to the public from 8 a.m. to 1 p.m., in a windowless room behind a pair of blue swinging doors near the plant’s entrance. Where décor’s concerned it’s got all the charm of a factory worker’s canteen, but who’s here for the ambience?

First up: boxes of vacuum sealed fish, under both the Acme and Blue Hill Bay labels, jars of marinated salmon and other packaged products at steep discounts. Like $6.50 for a half-pound of Scottish salmon that fetches $10 at Fairway, or $5 for a pound of whitefish salad. There’s wild salmon too—Coho, King and Sockeye—for $4.50 a quarter-pound.

Moving on: cardboard boxes piled with whole, golden-skinned trout, whitefish and whiting that top out at $7 a pound for the jumbo whitefish. Not for those who don’t like to buy their appetizers with eyeballs still attached, but the moist, smoky flesh is a must otherwise.

Finally: at the end of the line, near a rolling cart where ruby flanks of salmon are stacked like cordwood (above), are gorgeous slabs of fish including hot and cold smoked tuna, sable, bluefish and salmon in a half-dozen varieties, including gravlax, pastrami-style, and honey-baked as well as your basic smoked. Samples are set out, and the friendly, hair-netted women staffers are happy to offer more. They don’t thin-slice it surgically like the countermen at Zabar’s, but at $12 a pound—cash only—it’s nearly a third the price. Direct them where to cut for the right-sized hunk, then watch in wondrous gratitude as they wrap it up in paper. Pay, in cash. Eat. Repeat.

Acme Smoked Fish, 30 Gem St., Greenpoint, Brooklyn, (718) 383-8585.