Dead fish floating in the lake near the Olympic site
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Thousands of dead fish found in lake next to Rio's Olympic Park

23 August 2013 Last updated at 15:11 BST

Thousands of dead fish have been found floating in a lake near to where Rio's 2016 Olympic Park is being built.

Biologists think untreated sewage dumped into the water could be to blame.

Daniel Gallas reports.