He said officers were taking weekly samples from the affected areas to monitor biotoxin levels in the water or in the mussels.

“Current analyses by the Kuala Lumpur Fisheries Biosecurity Centre and the Fisheries Research Institute laboratory in Batu Maung, Penang, consistently indicate high biotoxin levels,” he said.

He said the samples contained the harmful Alexandrium algae.

On April 2, the Negeri Sembilan health department reported eight cases of food poisoning linked to mussel consumption.

Subsequent laboratory analyses revealed that mussels from the affected areas were contaminated with biotoxins and harmful algae species such as Prorocentrum, Alexandrium and Pseudo Nitzschia.

In another development, Adnan cautioned against releasing “ikan bandaraya” or plecos into rivers, as they could disrupt the ecosystem of native fish species.

He said the department recommended two methods for disposing of plecos: burying them in appropriate locations or using them as plant fertiliser or feed for farmed fish.

“The public can contact any nearby fisheries office for assistance with disposing of large quantities of plecos,” he said.