There is an undeniable charm to the notion that Mike Stollenwerk and his crew can produce sophisticated seafood at microscopic Little Fish, his hit BYO in Bella Vista that's so small it routinely turns away more diners than it actually feeds.

But a guy with Stollenwerk's considerable talent can be excused for mulling the possibilities of a second, more spacious home.

A walk-in fridge? That would be a dream. Enough prep room downstairs to debone a 40-pound halibut, with enough seats in the dining room to actually move it in a couple of days? Oh yeah! How about a few chef toys like an immersion circulator? Get the vacuum bags ready. And what about a liquor license to stock some interesting wines, high-end cocktails, and good craft beers? Any chef who's figured out how to squeeze a living and some acclaim from a 22-seat BYO can be hearing only one thing from that scenario: ka-ching!

Well, Stollenwerk has the answer to that wish at his new westside haunt called Fish. At 47 seats, it isn't exactly huge. But in this sleek but austerely retrofitted space of the former Astral Plane, we finally get a taste of what Stollenwerk can do with a full-service restaurant and a little breathing room. And it is promising.

Butter-poached lobster came one night over glazed salsify and snappy beech mushrooms ringed by a decadent red wine enriched with foie gras. As good as that was, I even preferred an earlier lobster app, a toothy mound of homemade cavatelli tossed in a coarse chop of lobster "Bolognese" tossed in crustacean-infused tomato ragu.

Tender sheets of octopus carpaccio, arranged like a tiled mosaic, made every garnish pop with vibrance, a sweet-tart burst of grapefruit, the peppery tingle of microgreens, the bright grassy fruit of olive oil. Crispy threads of fried chicken skin lent their distinctive crunch to classic goat cheese and beet salad.

I do wish the extra-tart Banyuls mignonette had been served alongside those gorgeous East Coast oysters from Falmouth, Riptide, and Martha's Vineyard (instead of splashed on top). But for the neighborhood surrounding the former Graduate Hospital, simply having such a great raw bar is a boon, with an ever-changing array of eight oysters drawn from both coasts served chilled atop little steel troughs of ice. The lemon-cucumber mignonette had a soft-spoken tang that was perfect for the more delicate West Coast Hog Islands.

While direct menu overlap is rare, the flavors here aren't yet especially distinctive from those at Little Fish, which former sous chef Chad Jenkins now runs as a partner. And there's plenty of room still for Stollenwerk to put some separation - in techniques or inventiveness, style or rarity of ingredients - between the two ventures.

But Little Fish already sets a high standard. And the westside crowd is lucky to experience that in a more comfortable setting that won't leave their clothes smelling like seafood from the open kitchen. Not that the dining room is especially warm - in fact, it's a bit austere (especially compared to the funky old Astral Plane).

Fish, however, has made good use of its liquor license and the convivial front bar that was always Astral's best space. There are good craft beers (Dupont, Brooklyn, Stone) and some well-made cocktails to choose from, like the cherry-kissed Frankfort Manhattan made with Basil Hayden's bourbon and Carpano Antica vermouth.

The moderately sized but well-chosen list is also brimming with seafood-friendly wines, including several under $50. Everyone likes a bright and lightly fizzy vinho verde from Portugal (Fuzelo, $7 a glass), but try the unusual Frédéric Giachino white from the French Savoie ($35), which is like a squirt of mineral and lemon for your oysters. Or a lush California viognier from Barrel 27 ($42). For big spenders, there are choices, too, from Dagueneau Pouilly Fumé ($68) to a fantastic Paul Goerg Champagne ($85).

Of course, the pleasant servers could use a little more training here - any specific request for wine advice sent them hustling back for a confab at the bar. Another server didn't even serve our wine until well after the appetizers had been served.

A little finishing polish, Fish still needs. Along with the front of house staff, the desserts need fine-tuning. They're satisfying enough in a chocolate torte kind of homey way (the goat cheese cake was my favorite), but not at the same level of sophistication as the savory fare.

Still, our meals here were very impressive overall - enough that Fish could easily rise to the next rating level by a year-end revisit. This is largely because Stollenwerk already ranks among the city's best seafood cooks, with a keen eye for vivid combinations that make his ingredients shine.

A cracker-skinned and flaky suzuki (Japanese bass) came over creamy orzo filled with tiny clams, crispy nuggets of house-cured bacon, and a spicy flicker of fresh fresno chiles threaded with preserved lemon. Pan-roasted monkfish were paired with an earthily exotic Madras curry of butternut squash, mussels and chewy couscous beads of fregola sarda. Crisply seared skate wing over spaetzle in parmesan broth practically fanned the aroma of shaved French truffles, the decadence was so intense. Red snapper with gigante white beans, piquillo peppers, and cuminy chorizo was evocative of a Spanish pantry.

Two simpler offerings - a Thai-curried mussel pot and a classic bowl of fines herbes-steamed littlenecks - proved familiar doesn't equal dull. With attention to great ingredients (like those slightly larger but more flavorful wild littlenecks), these alone were worth returning for.

There were a handful of less exciting efforts. The mahi mahi with chickpeas was overwhelmed by its piquant Mediterranean flavors. The peekytoe crab-filled ravioli clashed with the intense sweetness of its reduced carrot juice sauce. The roasted Loch Duart salmon over brussels sprouts and potatoes was so plain I could tell the chef was bored (as he later conceded over the phone).

There is nothing boring, though, about the inventive update on the Italian classic vitello tonnato. Usually a cold plate of sliced veal topped with tuna-flavored mayonnaise, at Fish it is instead ruby rare tuna loin wrapped in a seamless skin of veal cutlet. Meat glue and Stollenwerk's coveted new immersion circulator are involved, and the resulting Franken-fish is more about neat trompe l'oeil trickery than any deep flavors. Tuna's natural meatiness is heightened, but the veal itself is merely a wrapper. It's definitely tasty with grilled mushrooms and polenta, but still shy of brilliantly delicious.

And yet, I sense in this dish a chef in the throes of exploration beyond the usual seafood pan-roast, a cook headed somewhere new. With the space now to indulge those aspirations, I'm hoping the man from Little Fish continues to dream big.

Contact Craig LaBan at 215-854-2682 or claban@phillynews.com.
A third bell was added to this review after a revisit.