MIAMI, June 5 — In the hour before dark, the water in the canal is almost black, the kind of water a person hates to fall into, even in dreams. Six fishermen languidly fling lines baited with wriggling, palm-size bream into the murk, and now and then one will hook a nice bass. The others nod in admiration. "Cerveza?" one will ask. "Sí," the one with the fish will say, and beer tops will pop, lines will plop back into the water, and the ritual will repeat itself. A stringer of fish splash in the shallows, and the only other...