Ayhan Hassan, Nassau’s king of kebabs, is banking on something new.

Hassan, whose casual Mediterranean-style restaurants dot the county, has retooled the former Ayhan’s Fish-Kebab. It’s now Fish on Main, subtitled an “American Seafood Grille.”

More important, he has brought in John Brill, whose cooking earned two and one-half stars for Jack Halyards in Oyster Bay in 2013 and, in 2005, three for the departed Blue Lagoon in West Babylon.

Fish on Main’s setting is an airy, two-story, columned and converted bank building. The entryway and exposed-brick room are decorated with eye-catching white sculptures of finfish done in relief. Come spring, alfresco, or at least open-door, dining is likely. In April, a sushi bar is expected.

The differences between Fish-Kebab and Fish on Main are almost ingredient by ingredient. During recent visits tilapia made no appearance, calamari marinara surrendered to kung pao squid, and Sriracha sparked sauce for a shrimp cocktail.

Brill prepares a savory Manhattan seafood chowder, generous, well-seasoned and amply but not overly tomatoed. Grilled octopus arrives gently smoky, caught in a net of frisée, tangled with nuggets of chorizo, plus fennel and celery. And the house version of linguine with white clam sauce successfully enters the intense local competition.

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Crabcakes are more tightly packed than loosely bound, but satisfactory. That kung pao calamari has crunch from peanuts, though the sauce is syrupy and much more sweet than spicy. Skip ahi tuna nachos, which mask the flavor of the tartare with an overdose of extras, from wasabi cream to jalapeños. Stuffed jumbo shrimp disappoint, dulled by a pasty packing of crabmeat.

Brill’s affection for spice, Cajun variety, shows in a hybrid main course, penne jambalaya. The pasta is respectable, and a vehicle for the lively combo of andouille, smoked chicken and shrimp in a tomato-cream sauce. Bayou swordfish means a triangular slab capped with hollandaise sauce that has a hint of crawfish. But the dirty rice on which it rests is pretty dry. You’re better off with the straightforward, moist, grilled swordfish.

Miso-maple “lacquered” cedar-plank roasted salmon has the requisite sheen, and good flavor. Sesame-seed crusted tuna, now as familiar as stuffed flounder used to be, benefits from the wasabi-spurred mashed potatoes. Delicate whole grilled branzino tastes fine, though the split-and-splayed look suggests an autopsy in progress. If you’re adamantly against seafood, try the herbaceous, pan-roasted chicken breast with gnocchi.

The big dessert here is a hefty wedge of chocolate layer cake for two. Fittingly, a high-rise, sometimes on its side.