REPUBLIKA.CO.ID, LUBUK BASUNG -- The fish farmers in Lake Maninjau, Agam District, West Sumatra, have suffered losses of about Rp 66,5 billion. Their fish died suddenly in the lake since a week ago.

"Approximately 3,050 tons of fish belong to fish farmers in Lake Maninjau died suddenly since last Friday (8/26)," Head of Marine and Fisheries Department (DKP) of Agam, Ermanto, said in Lubuk Basung, on Saturday (3/9).

Those fish was cultivated at floating cages plots. He added, DKP has given a warning letter to harvest the fish early and asked farmers to reduce stocking from 20,000 per plot into 2,000 a plot with size of 5x5 meters.

"We have given the letter before August 2016," he said.

The death of fish, according to him, are due to sulfur intoxication, the activation of base, and the fish have suffered oxygen deficiency. In addition, the floating cages in the lake was over capacity. 

In accordance with the regulations and research from Indonesian Institute of Sciences (LIPI), the lake is only able accommodated 6,000 plots cages. However, the existing floating net had reached 18,000 plots with a size of 5x5 meters.

"Calm lake waters and no waves cause oxygen deficiency," he said.

He urged fish farmers to reduce the amount of floating net cages, set the distance about 10 meters, and set the cages distance from the beach about 200 meters.

"Fish farmers need three months in a year time lag to cultivate fish, such as from August until December," he said.