The local press reported that the worst red tide-induced fish kill in Hong Kong\'s history had destroyed over 1,500 metric tons of maricultured fish stocks. The Hong Kong Government estimated the fish farmers\' losses at HK$80 million (US$10.3 million), but fish farmers claimed the figure was at least HK$250 million (US$32 million). About 1,000 of Hong Kong\'s 1,500 fish farms were devastated by the Gymnodinium mikimotoi red tide. The red tide "spread out like an infectious disease,\'' stated Hong Kong Fish Culture Association Chairman, Wong Yung-kan. Phytoplankton samples taken near the fish mariculture cages at Mo Tat Wan on 15 April 1998 contained over one million cells L-1 of Gymnodinium mikimotoi. At high densities, the G. mikimotoi produced a sticky mucus. When the mucus touched plant fibers or chitin or other dinoflagellates it stuck to them. When it made contact with the gill filaments of fish or shellfish it asphyxiated up to 90% of the impacted fish within 30 minutes. This rapid mortality gave rise to speculation that the slime contained a phycotoxin. The gills of the dead fish that were examined were coated with dinoflagellates trapped in their own slime. The reason that dinoflagellates produce copious amounts of a sticky mucus can be inferred from photographs taken at the peak of the 15 April bloom near Lamma Island where the Hong Kong mariculture industry was particularly hard hit. The photographs indicate that the secreted mucus sticks to inanimate objects such as plant fibers as well as to living objects such as the chitinous exoskeleton of copepods. The grazing efficiency of copepods with G. mikimotoi slime attached to their carapace is considerably reduced. Thus, mucus production may increase G. mikimotoi (dinoflagellate) survival by reducing the filtering efficiency of predatory copepods or by assisting dinoflagellates to form long chains or large mucus covered balls which are too large for most predators to handle.