About 1,510kg of evil eye puffer fish have been removed in False Bay and there is now a significant decline in puffer fish mortalities since a mass washout three weeks ago.

City of Cape Town mayoral committee member for spatial planning and environment Marian Nieuwoudt told SowetanLIVE's sister publication TimesLIVE the event appears to be coming to an end.

Thousands of fish mysteriously washed ashore, prompting the city to begin a mass cleanup and issue a warning against puffer fish consumption for dogs or humans due to their toxicity.

The department of environment forestry and fisheries (DEFF) said there were no adverse water conditions like pollution or red-tide toxins that may have caused this these large-scale mortalities.

It initially indicated the washouts may have been due to mass courtship; spawning and fighting which sees the male puffer fish inflate themselves and sometimes get rolled or blown out of the water by waves or wind.

However, the department has discounted this theory due to the high volumes of puffer fish washouts.

“Scientists are now discounting this and considering other causes. Samples of fish have been taken and tests are being conducted. At the moment, the city can therefore not confirm the exact cause of the mortalities,” said Nieuwoudt.

The Glencairn Veterinary Hospital in Fish Hoek said on Wednesday it had treated at least 10 dogs who had come into contact with the toxic fish, with more having received treatment from other facilities in the city. It confirmed one fatality.

The hospital issued a warning to dog owners urging them to keep the animals leashed when on the beach or avoid beaches altogether until it's safe to go there again.

Nieuwoudt also warned that the puffer fish carried the neurotoxin tetrodotoxin and should not be eaten. The American Center for Disease Control says tetrodotoxin causes paralysis of body muscles and can be fatal.