FISHERMEN setting out to sea without a supply of potassium? An impossibility, the pirates might say. Potassium cyanide is glorified by fishermen in developing countries, because it is considered an effective aid for netting fish. Just spray the chemical into the water, wait a few moments, then watch the dead fish float to the surface before harvesting. It's easy on the wallet, takes little effort and huge hauls are made. This is a credo held b