The world’s coral reefs are threatened by consumers seeking tropical fish and coral for home aquariums, scientists said yesterday at a reef protection conference organized by the U.S. Home aquarium owners, mostly Americans, are buying live coral at a rate that has been growing by 12 to 30 percent a year since 1990, according to reports to be presented today at the meeting. Provoked by consumer demand, divers are using illegal harvesting methods, often squirting cyanide into reefs to stun sought-after fish, killing smaller fish and coral in the process. Recent studies indicate that a variety of problems have caused 10 percent of the world’s coral reefs to become degraded beyond recovery, and that nearly two-thirds are being damaged by human activities, the National Oceanic and Atmospheric Administration says. In other disheartening fish news, the U.S. Commerce Department says a record 98 species of fish in U.S. waters are being depleted by overfishing.