Thousands of dead fish filled a river in Paraguay over the weekend.
An investigation was launched to figure out what caused the massive flood of carcasses in the Confuso River in Villa Hayes, near Asuncio. Authorities pointed to several factories just upstream from the site as the potential culprits, theorizing that industrial liquid waste deposits could have been behind the mysterious deaths. Other experts believed a lack of oxygen in the water may have caused the incident.
Similar large scale fish deaths have happened recently in other countries.
In Chile in 2016, an algae bloom known as 'red tide' was identified as the reason for numerous aquatic deaths. The carcasses of more than 300 whales, 8,000 tons of sardines, and 40,000 tons of salmon washed up across Chile's beaches. 'Red tides' are common in Chile, and release a natural toxin that paralyzes fish. However, years past had not seen such vast devastation from the algae. Experts were unsure whether the events could be traced back to fish farming methods, or whether abnormalities in sea temperature carried the blame. The catastrophic scale of the 'red tide' led fishermen to demand compensation for their loss of business.
Costa Rica also saw numerous cases of mass fish deaths throughout 2016. A swath of various species were found dead in several rivers in one case, leading some to speculate that sudden water temperature changes and a decrease in oxygen levels were to blame. But scientists later reported that contamination from agricultural chemicals, as well as illegal fish farming practices, were behind the widespread fish deaths.
In Brazil in 2015, 50 tons of fish were removed from the sewage-filled waters of a Rio de Janeiro lagoon. The location was intended to play host to numerous Olympic venues the following year, and the potential hazard sparked outrage as event organizers tried to quell health concerns.