Rio de Janeiro, March 1 (IANS/EFE) Up to 40 tons of fish, that died apparently due to lack of oxygen caused by excess growth of algae, was removed off the coast of Rio de Janeiro, authorities said.

According to Brazil's environment department official, the cause of sudden, massive extermination of fish has not yet been ascertained, but it could have been caused by the unusual proliferation of algae, which have reduced the oxygen content of the water.

Friday, thousands of fish appeared floating on the waters of Rodrigo de Freitas Lagoon, a tourist attraction near the beaches of Copacabana, Ipanema and Leblon, the Urban Cleaning Company of Rio de Janeiro said.