Almost twenty years ago Mark Zaslavsky and Mark Gelman opened what has become one of the finest caviar businesses anywhere. Except it isn't one business. There's the exceptional retail section (known by insiders as "the Russian store," although it caters to many Eastern Europeans and anyone else with good taste and the money to afford delicate delectables). There's a wholesale department. There's the importing business, which involves sending representatives to Russia on a regular basis to inspect the fisheries, processors, and dealers in an effort to assure that Marky's acquires only the finest fish eggs in the world. There's the online business. And when the sturgeon population began sinking a few years ago, the Marks built their own fish farm in a small north-central Florida town called Pierson. The company requires DNA tests on each batch of roe, and has every certification imaginable. Beyond that, Marky's also offers high-grade foie gras (duck and goose), smoked salmon (three types), truffles, mushrooms, cheeses, and so on. (Kosher versions of most items are available.) But the sticky little eggs are the heart of the Marks' operation: the famous osetra; small, grayish sevruga; salmon; paddlefish .... Most of the roe comes from a giant fish farm in the delta of the Volga River. The most important undertaking, according to the owners, is what they call "restoration of the world's resources of sturgeon." Hence the aquaculture operation upstate. When it comes to the highest-quality, most carefully controlled caviar, Marky's can't be topped. They do everything but lay the eggs themselves.