CHRISTIANSTED, U.S. Virgin Islands -- Home aquarium owners, most in the United States, are threatening fragile reefs by buying up tons of the world's coral and tropical fish, experts say. Enthusiasts are buying up live coral at a rate that has increased 12 to 30 percent a year since 1990, according to reports to be presented Tuesday at a U.S. government conference on coral reefs.

The demand to fill fish tanks is fueling a thriving trade in illegal harvesting, with divers squirting cyanide into reefs to stun fish and killing smaller fish and coral in the process. Only one in 10 captured fish survives, researchers from the U.S. Coral Reef Task Force said. "Hobbyists have a love of these critters," said Roger Griffis, a Department of Commerce policy analyst. "If they knew it was harming the reef, they would be appalled."

The U.S. Coral Reef Task Force is meeting on the U.S. Virgin Island of St. Croix to consider ways to preserve reefs and mull reports by its committees of scientists, business leaders and government officials. U.S. Interior Secretary Bruce Babbitt is to address the conference Tuesday. Earlier conservation efforts have focused on threats like pollution and global change. But early arrivals at the conference Monday said aquarium enthusiasts are becoming a real threat.

Two-thirds of the world's 1.5 million aquarium hobbyists live in the United States. They buy half of the aquarium fish and up to 80 percent of the coral traded in the world, the task force's committee on international trade said. The next largest importers are Germany and Japan. Since the United States bans harvesting of coral in its own waters, most of the supply comes from loosely protected reefs in poorer countries. Most aquarium fish come from Indonesia and the Philippines, and more than half are harvested with cyanide in violation of local laws, the task force said.

The U.N. Convention on International Trade in Endangered Species regulates trade for 2,000 species of coral. But live fish, soft corals, anemones, crustaceans, mollusks and other creatures imported to the United States for the aquarium trade are not on the list. In September, the European Union temporarily banned imports of a half dozen coral species from Indonesia because of doubts over the country's claim that the environment was not being harmed.

Seahorse populations have dwindled by more than 25 percent since 1994, in part because of harvesting, the task force said. Twenty countries, including the United States, export seahorses for aquariums and to be used in folk medicines. The booming demand for fish has prompted the African nation of Mozambique to impose a ban on coral and aquarium fish exports until 2001. The Pacific island of Fiji is also reviewing export laws.

The Marine Aquarium Council, a Honolulu-based umbrella for conservation groups, marine industries and government agencies is calling for a certification program. That would create a paper trail so that buyers know their fish were harvested legally, said Paul Holthus, the council's executive director. Currently they have to "trust what they are being told" by sellers, he said. In one report, the task force recommended increasing the number of Fish and Wildlife Service inspectors at ports and testing fish for cyanide.