SEREMBAN: Excessive algae growth amid prolonged hot weather and a lack of rainfall has caused the river water in Mukim Pertang, Jelebu, to turn green, according to the Negeri Sembilan Department of Fisheries (DOF).
Its director Kasim Tawe said investigations found that the change in water colour was not caused by pollution, but by green algae growth in nearby fish ponds due to the prevailing hot weather.
"The DOF has taken the initiative to monitor the area, as green algae growth in fish ponds can have either positive or negative effects depending on the density and species of fish.
"This algae does not pose a danger to fish and, under controlled conditions, provides dissolved oxygen and serves as a natural food source, while helping to improve water quality,” he told Bernama here on Tuesday (Aug 25).
Kasim said algae also acts as a natural shield against the sun’s rays, helping to reduce stress on fish.
He said, however, that uncontrolled algae growth could cause dissolved oxygen (DO) levels to fall rapidly, particularly at night, as well as trigger sudden fluctuations in water pH, potentially resulting in clogged fish gills.
Kasim said fish breeders should take several measures to control algae growth, including using waterwheels, particularly at night, changing the water gradually, reducing feeding, installing shading nets, applying beneficial bacteria (probiotics) and reducing the fish population in the ponds.
He said the Jelebu District Fisheries Office, together with the Pertang Police Station, would continuously monitor the river and fish ponds to ensure the situation remained under control.
The former mining pond is used for breeding baung, red tilapia and Lee Koh fish, covering a total area of approximately 29.54 hectares.
Earlier, a screenshot of a WhatsApp message regarding the change in the colour of the river water in Mukim Pertang, which was suspected to have been caused by the discharge of water from nearby fish-breeding ponds, went viral on social media.- Bernama
