Fifteen tons of dead fish was removed from a section of Zeekoevlei between Friday and Monday afternoon.
The situation was reported to the City of Cape Town who then had lab tests done finding that the fish died of natural causes. In a statement released by the City, they confirmed that only one species of fish died.
“Fish kills, which refer to a localised die-off of fish populations, often occur at this time of the year with the change of seasons when water levels are low and temperatures are high. Fish sometimes become stressed during breeding and they may pass on infectious disease due to the grouping of large numbers of adult fish together,” the statement read. Mayco member for environmental and spatial planning Johan van der Merwe said an estimated total of 20 tons of carp have died and would be removed by the end of today.
“It is expected that all of the dead fish will be removed by today provided that there are no further deaths. We will continue to monitor the site on an ongoing basis,” Van der Merwe said.
The State Veterinarian is currently processing samples of the dead fish and the laboratory analysis of these samples is being awaited upon.
“Although the official cause of death has not yet been confirmed, the symptoms of the carp are consistent with the previous koi herpes virus outbreaks that have happened in some of Cape Town’s marshes. The koi herpes virus is known to be present in carp populations in Cape Town. The disease is often dormant and is triggered by certain environmental conditions which result in the carp die-offs which have been witnessed in previous years,” he says.
Residents were urged not to eat the fish and to stay clear of the area while the fish were being collected.
“In addition the public is reminded that only non-contact or partial contact forms of recreation, which include sailing and rowing, are advised in Zeekoevlei and Zandvlei as well as other urban marshes which are often affected by pollutants,” Van der Merwe says.
Lab results indicated low traces of algal toxins well below the guideline limits in the affected area.
Samples taken also indicated no toxins present in the affected area. The fish bodies were transported to the City’s Vissershok landfill site. There has also been a fish kill reported on another unconnected system (Keysers River/Westlake/Zandvlei area). Pictures of the dead fish went viral on Facebook on Friday resulting in outrage from residents.