Laurent Tourendel has finally opened the top-floor formal dining room of his fish-focused bistro BLT Fish, two floors above the already-acclaimed lobster shack-themed eatery on the first floor. The top tier’s opening would seem a fitting metaphorical progression for Mr. Tourendel as he sets his sights on reclaiming the crown he once wore as one of the city’s poissonneries extraordinaires, back in the days when he dazzled seafood lovers at the Upper East Side’s Cello, which existed from 1999 to 2002. Installed in the space that in previous incarnations was the supermodel filled roof deck of Flowers and subsequently the glass-capped dining room of A-Z, BLT Fish’s feel is more elegant and polished, appointed in tones of beige and cream suede that soak up the daylight beautifully through the panels of the retractable glass ceiling that, even at night, manages to render the space light and airy.

From the ground-floor bar, where we were asked to wait for our table one night last week, we were escorted onto the elevator by a host who offered to carry our drinks. Once we entered the third-floor dining room, Mr. Tourondel was in plain view, commandeering a gleaming open kitchen alongside the chef de cuisine, Mathieu Palombino. The effect is similar to that at Jean-Georges, where Chef Vongerichten can often be seen working.

Feather-light Vermont cheddar-chive biscuits arrived piping hot, accompanied by a square of salted butter sitting in a pool of warm Vermont maple syrup, which set the tone for the rich, creative dishes ahead.

Appetizers showcased Mr. Tourondel’s mastery of technique. A mound of glistening coral pink spicy tuna tartare ($14), crowned with preserved lemons, avocado, and American caviar, was served with six-inch-long Idaho potato chips for slathering. While the salted crisps added another clever contrast to the creamy tartare, I found myself wanting to eat it directly from a spoon like dessert.

Grilled sardines with bacon, tomato, and basil ($12) sounded far heavier than what was delivered; the meaty fish was tame in flavor and exquisitely fresh, taking on its accompaniments without being overwhelmed. A salad of tender grilled octopus ($18) was smoky and light, tossed with an orange-bergamot oil vinaigrette that was nicely fragrant. Another salad made with Nantucket bay scallops tossed with Port poached pears, Fourme d’Ambert cheese, and walnuts ($14) was more formidable in both flavor and character.

The main courses, with two exceptions, are all fish dishes, divided on the menu into categories of “Whole Fish & Shellfish,” sold by the pound (averaging 2 to 3 pounds each), and more conventional “Fish” selections sold in filleted portions. The beautiful whole fish are simply grilled with olive oil and sea salt, then either served whole on the bone or filleted tableside as you wish. George Calle, a consummate waiter who has worked with Mr. Tourendel since Cello, recommended we order the crispy whole red snapper prepared Cantonese-style ($31 a pound), an unusual twist on this otherwise straightforward menu, and we’re glad he did. The magnificent 2.5-pound fish was presented skewered in an S-pattern, to look like it was still swimming, its mouth wide open, flashing its tiny teeth. A thatch of cilantro greens was placed on its head, giving it a whimsical hairdo that looked almost punk-rock. It was then filleted and served, along with the cilantro and fabulous sauce comprised of (at least) scallions, ginger, onions, and sweet soy sauce. It was nothing short of fantastic.

A meaty slab of Alaskan black cod ($28) was amazingly good, too, bathed in a curry-lemongrass sauce that was just pungent enough. Other fish available included Mediterranean loup de mer ($28 a pound), Pacific John Dory ($29 a pound), Belgian Dover sole ($34 a pound), and Icelandic Halibut ($32 a fillet).As at his BLT Steak uptown, Mr. Tourondel offers a host of luxurious sauces as condiments for his mostly minimally prepared dishes, such as tomato-tarragon hollandaise and lime-cilantro mayonnaise, as well as classic caper-brown butter sauce and pesto.

Vegetable sides here (all $8) are as sumptuous as they are at BLT Steak, including salt-crusted sunchokes, sauteed garlic and spinach, braised celery stalks, and a creamy parsnip puree. Starches (all $7) include the over-the-top parmesan-dressed gnocchi, which manage to remain light despite the sauce; ethereal silver dollar fried potato chips; and a crispy rice gallette that was a small meal in itself.

Not to be overlooked is Fred Dexheimer’s wine list, categorized by both aromatic style – such as “rich, savory, complex” whites and “soft, fresh, smooth” reds – as well as by grape varieties, it’s user-friendly for connoisseurs and amateurs alike. Most helpful of all is a short list of around 40 bottles featuring Mr. Dexheimer’s favorites under $100, many of them priced under $50.

Desserts (all $9) include a cloud-light caramelized meringue with a banana-passion fruit sorbet; lime-scented millefeuilles with a mouthwatering lime syrup sauce; and a magnificent grapefruit tart with honey-lavender cream. Treats at the end include a plate of tiny beignets and chocolate truffles and a jar containing a puff of green apple cotton candy that was the essence of Granny Smith.

BLT Fish, 21 W. 17th St., 212-691-8888.