How the humble sablefish, a deli bargain, became black cod, an haute cuisine staple and the most valuable catch in the world

THERE ARE PLENTY OF FISH IN THE SEA-some 27,000 species, to be precise-but you'd never know that from looking at a menu. We consume seafood the way we love. In both cases, we tend toward serial monogamy, and the consequences for our finny friends can be dire: we find a species we like and eat it to extinction, then we move on to the next catch.

In the '80s, salmon dominated Toronto's menus and fish counters. But growing demand led to farmed, flabby blandness. Today, no self-respecting gourmet would be caught dead ordering the so called "chicken of the sea"-unless it were organic Irish or line-caught Copper River spring run. Chilean sea bass was the it-fish of the '90s, until reports of commercial extinction forced conscience-stricken diners to give up its rich, meaty, white flesh.

Now there's a new fish in town that's nearly as opulent in texture. Actually, it's an old fish with a new name. A decade ago, black cod was better known as sablefish, and most of its northern Pacific population was sold in Japan. Because of protective fishing laws, it had to be caught in the space of a few weeks, creating a glut in the market-and our freezers. No wonder it was better off smoked and sold cheaply to delis.

Sablefish didn't have any haute cuisine cred. Ned Bell, a brief but bright food star in Toronto in the late '903, remembers thinking that the city's top restaurants were "game forward but seafood conservative." In 1997, when he and Vancouver celebrity chef Rob Feenie opened Accolade, the hotel InterContinental's short-lived experiment in avant-garde dining, they put fresh black cod on the menu but had to order it directly from an Indian band on the West Coast.

At the time, sablefish was also gaining notoriety in New York. Chef Nobu Matsuhisa, well on his way to becoming the rock star of the sushi world, made it his signature dish at his eponymous TriBeCa raw fish mecca, soaking it for days in a sweet-sour marinade of miso, mirin, sake and sugar before broiling it to caramelized perfection. He was one of the first big chefs to call it "black cod, " which sounded more sophisticated than deli sable. (Though it bears some resemblance to members of the cod family, it isn't kin.) Suddenly, what had been a cold-weather delicacy on the far side of the Pacific (where it had been considered too heavy for summer) became a hip, year-round staple across Manhattan. By 2001, New York Times writer Marian Burros had dubbed it "the Cinderella of the seafood world."

Toronto chefs always have their eye on New York, so it wasn't long before miso-marinated black cod appeared around this city. It was an obvious dish for Rain, with its Asian-influenced cuisine and edgy attitude. In 2001, chef Guy Rubino served it sizzling on a river stone, refreshed by a tangle of tatsoi and daikon sprouts (a version of Rain's "miso cod" remains on the menu today, making it Rain's longest-lasting dish). Likewise, it was a natural fit for Lee, where a pinch of Cantonese preserved vegetables cuts the unction. (Black cod suits Lee's small dishes, which are meant to be shared-a whole plateful can be too much of a good thing.)

Yorkville's Flow and downtown's George, two other trend-conscious restaurants that opened last year, also give a nod to the cod. The latter's version is encrusted with pecan, served with a mango relish and potatoes braised in a truffle broth (as much as restaurateurs like to copy New York trends, chefs still like to play with their food). At Canoe, Anthony Walsh makes black cod part of a novel surf'n' turf, setting it next to oxtail, another humble food turned haute.

Black cod's newfound popularity with chefs can also be chalked up to a relaxing of the fishing laws, which extended the season for catching the fish. In the early '90s, it became much easier to buy black cod fresh or frozen at sea year-round. So when Chilean sea bass became verboten, chefs and environmentally conscious home cooks knew where to turn for a doppelganger. "It's now the number one alternative," says Dave Jung of Pisces Gourmet, the pristine Summerhill market. "It's very juicy, sweet and mild flavoured, but a little more flaky." Not that he doesn't still sell Chilean sea bass: hardcore fans continue to buy it secretly for the family, opting for black cod when entertaining, so as not to offend dinner guests.

As demand grows, so does the price: Pisces sells black cod for $25.99 per pound, more than three times the cost of salmon. But, happily, the wild population remains stable: drop a line of hooks into a school and each one will come up with a catch. The B.C. government is nevertheless allowing the conversion of some farms from salmon to sablefish - an unnecessary preemptive strike that worries fishery experts who know how the salmon experiment turned out. "We're starting to see small amounts of farmed black cod on the market," says Jung. "But I don't like it as much-the texture is softer, flabbier, and the fish are a lot smaller." So eat wild while it's well managed-there's no need to put it on the endangered list. But if, one day, the black cod species does become scarce, you can be sure we will switch our fickle affections to another.