Rio de Janeiro's environmental authorities say the amount of dead fish removed from a lake where the Olympic regatta will be held in 2016 stands at more than 60 tons.

Rio's municipal department of the environment says in a Thursday statement that since Monday the 65 tons of have been removed from the Rodrigo de Freitas lake. The lake located in the heart of the city is among the area's many tourist attractions.

The department says that a earlier this week washed organic matter into the lake, leading to the big die-off of the fish.

It says the situation is improving and that no dead fish were pulled out of the lake on Thursday.