AQUACULTURE, once eulogised as a trouble-free money-spinner, is now causingsleepless nights for its promoters. Lastyear, a mysterious viral disease, nick-named "white spot", had swept TamilNadu, Andhra Pradesh and Kerala, decimating a large part of the culturedshrimp crop. After ravaging the industryin West Bengal, the scourge has recentlyaffected the prawn farms of Karnataka'sUttar Kannada district. The genesis ofthe outbreak has been traced to infectedprawn seeds released by an aquaculturecompany in the Aghanashini river. Thedisease has left farms in the district'sKumta taluk, through which the riverflows, full of dead prawns. The aquaculture industry in other Asian nations issimilarly afflicted. Taiwan, the world'slargest shrimp exporter till a few yearsago, has seen its output fall from 90,000metric tonnes (mt) in 1987 to 25,000 mtin 1989 owing to a disease-hit industry.Experts say intensive production, toorapid an expansion, overexploitation ofgroundwater and self- contamination ofthe water in the farms have led to the outbreaks.