As diners enter Heads or Tails Seafood, they're greeted by a smoky fish-fry aroma with an underlying scent of raw fish that emanates from the retail market located immediately to the right. The menu, printed on a paper placemat and set in front of each patron, translates into: fish, fish, and more fish, either griddled or fried. If you must, flip a coin to decide, but it doesn't really matter which way it falls - you can't lose. The only full-size hot appetizer is a plate of fried calamari, which almost everyone seems to order. It is an enviable version, the rings lightly dusted with flour and crisply flash-fried. Other warm selections are dominated by a fried assortment of fritters and croquettes for $1.00 each. Main courses are accompanied by varying choices of red or black beans, French fries, plantains, tostones, mashed potatoes, salad, and white or yellow rice - that adds up to a sizable seafood meal for $6.99 to $8.99. New items include lobster with shrimp ($18.99,) conch with shrimp ($12.99,) and a quarter pound of jumbo shrimp ($10.99.) Great prices only partially explain why most of the stools remain occupied from noon through closing. Heads or Tails' popularity also rests on the unquestionable freshness and consistently adept preparation of its catch. Whole snapper and a half-dozen jumbo breaded shrimp are neatly fried and moist within. Thick wedges of dolphin and, even better, steak cuts of full-flavor kingfish (mackerel) are assertively seasoned and crisply griddled on a sheet pan placed over high heat. Even shrimp creole, which requires more culinary finesse than the other dishes, is inordinately tasty, the juicy crustaceans ribboned with onions and green peppers in a spirited garlic-and-bay-leaf-laden sauce. You can also order a grilled or fried fish fillet fluffed into a burger bun with lettuce, tomato, and onion; at $4.99, it's one of the savviest sandwich deals in town.