A cyanide spill in northeastern Romania has killed thousands of fish and now poses a health hazard to humans, government officials said yesterday. The spill occurred when the contents of a storage container at a recently closed chemical plant spread from a rain gutter into a tributary of the Siret River, raising cyanide levels in some places to 130 times accepted levels. Locals have been warned not to drink water from wells, and some environmental officials fear that poisoned fish may already have found their way to market.