At M Sushi, nothing behind the bar is out of place.

The row of sushi chefs in chambray getup dotting each station. Stacks of plastic white cutting boards and handmade porcelain plates. A few $800 knives used specifically for nigiri and sashimi. A neat collection of cookbooks on a back shelf. Condiments are in their respective plastic containers, right by the boxes of latex gloves.

And, for top sushi chef Magno Tapia, a face mask, so he can breathe easy. And if he can’t, hidden from view are a pack of antihistamine tablets and a couple of epinephrine pens.

“I’m just allergic to finned fish,” he says with a smirk made visible only by the corners of the paper mask over his mouth lifting ever so slightly. He slices through the belly of a salmon, chuckling at the irony.

“Some people that come in probably think I’m sick. ‘Why is he wearing that mask? He’s the only one,’” he says. “Back in the day I used to wrap my hands tight in plastic wrap.”

Symptoms of his allergy can range from a rash and hives to itchy throat and anaphylaxis, or severe trouble breathing. Tapia says he’s cautious. He can’t actually taste what he’s making, but with each morsel he cuts and places on a plate, he rattles off its characteristics as if he’s been eating sushi his whole life.

“This madaiJapanese sea bream,” he says. “It’s very clean, but at the end it has a sweet kick to it.”

He explains flounder next while he pulls out a blowtorch. “It’s too bland, too plain. I just don’t think it’s good. Now the fin of the flounderwhat’s the Japanese word for it? Engawa. If you lightly sear it, then it’s good.”

He moves onto kampachi from Hawaii. “I love this, by the way. It’s very creamy. Very creamy.” I ask how he knows that. He filets the iridescent flesh and lifts it up. I’m stumped.

“Put these gloves on, get back here.”

I oblige and press the filet with my fingers as he tells me to, looking for a crease that may smooth out any oils, an obvious indication of the creamy flavor he describes. I sort of feel it, but I quickly realize that the distinction Tapia can make with his hands, eyes, and olfactory senses comes from nearly a lifetime of experience.

Tapia started fileting fish when he was barely out of his teens, at Asuka in Morrisville.

“I was doing hibachi then, but they’d ask me at the sushi bar to help cut the cucumbers. And I saw my shot, so I go, ‘Hey, listen, why don’t you just train me at the sushi bar?’”

Asuka was pulling one hundred customers a day just during lunch rush, and Tapia began “falling for it,” he says. Looking back, Tapia says it’s the simple tradition of sushi that he’s drawn to, which he absorbs even further through books and YouTube videos about the craft.

By 2006 he had moved to Mura in North Hills, where M Sushi chef-owner Michael Lee was leading the sushi menu. Lee noticed Tapia’s potential and took him under his wing. They’ve been working together ever since.

“He was very young and energetic, barely of age to drink, and just a kid back then,” Lee recalls. “There were some old-school Asians who thought he was loud. But you have to ask lots of questions when you’re learning, so it never bothered me. He adapted well and learned to do things people wanted and needed from him without them explaining every single time. He developed street smarts for the kitchen.”

That street-smart mentality also meant surviving a fish allergy. Like every newbie, he started by learning to filet salmon.

“That’s the reason my hands were getting itchy,” he says. “My hands were always red. Then, if I would get poked by any of the bones, my fingers would swell up. I was really excited about it, and I didn’t care about the allergy. I just thought, I’m OK, I’m not gonna die. I’m just not gonna eat it.”

Tapia’s allergy grew over time. Strangely enough, he was born in Veracruz, a coastal region in Mexico where seafood featured prominently on his family’s table in stews and platters of fried fish. It wasn’t until he got to the United States as a teenager that, after a couple of spoonfuls of the stew he grew up with, his lips and face started to swell. Since then, he’s only had a few close calls.

With the help of Benadryl and, off-duty, a little alcohol, Tapia says he’ll occasionally have a few bites of fish. But not salmon, the biggest culprit.

“I wish I could eat it, but I don’t have the guts to do something crazy like that.”