KUALA LUMPUR, Aug 12 — In another case of water pollution, an estimated 50,000 fish were found dead in Teluk Bahang yesterday.

The cause of death is said to be heavy metal content that deoxygenated the water and breeders are estimating their losses to be RM800,000.

This is the second such case in Teluk Bahang since May when thousands of grouper fish were also found dead in their cages.

State environment committee chairman Phee Boon Poh confirmed the presence of heavy metals but said it was not excessive, according to The Star.

"No, not nickel. But heavy metal but within the permissible level. The death is due to a lack of oxygen,” he said.

Fish breeder Ooi Hye Hin, who was affected in May as well as yesterday, told The Star he saw his fish jumping out of the water at 1am yesterday and knew something was wrong.

In the morning, he found all his fish dead.

"It happened in May. Now, this is worse because all 50,000 plus of my fish are dead and none could be salvaged. They are worth about RM800, 000,” Ooi told The Star.

"I cannot resume this business anymore,” said Ooi, adding that he had been in the fish breeding business for close to 20 years.

Centre for Marine and Coastal Studies (Cemacs) director Prof Datuk Dr Aileen Tan said yesterday there were heavy metals detected during the May incident but not at levels high enough to kill the fish.

"We have detected the shift of phytoplankton diversity and also a high concentration.

"Sign of eutrophication (excessive nutrients) in the shallow bay which may cause the depletion of dissolved oxygen — excessive nutrients in the water (phosphate and ammonia).

"In our monitoring since then, the nutrient levels are still high.

"This time, it might be slightly different because of the strong current and waves from Typhoon Lekima might have stirred some toxins from the seabed,” she said.

Tan also did not rule out the deteriorating water quality in Teluk Bahang as the reason for the fish dying.

"Combined factors of toxins and low dissolved oxygen may have caused a stressed environment to the fish around the area,” Tan continued.

Cemacs science officer Sim Yee Kwang, who was part of the team of officers from Cemacs at Ooi’s site, said the water temperature, salt and pH levels were normal, but oxygen levels in the water was lower than normal.

"We will be bringing the fish and water samples back to USM for analysis,” he added.

Back in May, Cemacs had reported that the level of nickel was 1,038 per cent more than it should be in the seas near the Penang National Park and 982 per cent higher at the fish farms in Teluk Bahang.

The sea off Teluk Bahang is said to be contaminated by heavy metals while in Nibong Tebal, the water at the Sungai Tengah river mouth is black, a problem fishermen there claim has been plaguing them for about 10 years.

* A previous version of this story contained an error which has since been corrected.