Lake Maninjau in West Sumatra, Indonesia, is littered with thousands of carcasses as the fish "suddenly died" according to fishermen.

Footage from April 29 shows the bodies of dead fish floating on the lake's surface and washing up on the shore.

Further clips show the carcasses in the netted cages the fishermen keep their product in.

According to locals, the fish died due to reduced oxygen levels in the water caused by fish feed settling at the bottom of the lake.

One farmer, Syafrudin, said that they don't know whether poison is the reason behind the mass deaths.

In 2016 thousands of fish died due to strong winds and heavy rain that struck the area.

Millions of fish in floating net cages in Lake Maninjau, Agam district, West Sumatra, Indonesia suddenly died. Tilapia and goldfish are farmed fish belonging to keramba farmers in Sungai Batang village, Tanjung Raya sub-district, Agam district.

The fish has died since last Saturday (24/04/2021), and continues to expand to several other locations. As of Thursday (29/04/2021), the number of dead fish is estimated to have reached more than 100 tons.

The keramba farmers admitted that they did not have time to save their fish, because they could not predict this incident. Syafrudin, a floating cage farmer at Muaro Pauh said, Wednesday (28/04/2021) afternoon, he still feeds the fish and the fish still looks fresh. But at night, the fish suddenly died.

Even though the plan is that he will harvest the fish in the next few days. But unfortunately, before it could be harvested, the fish died first.

According to residents, the death of the fish was due to the reduced oxygen in the water, and it was exacerbated by the lake water which had been contaminated by the leftover fish feed that had long settled on the lake bottom.

“I have 6 plots, but as a family we have 18 plots, we can't confirm the dead ones. One plot is about 1.5 tons. The harvest is planned for this week. The reason is we do not know, whether the poison that arises, we do not know. This seems poisonous, because the fish comes out of oil, the oxygen is reduced, ”said Syafrudin, a floating cage farmer.

It is estimated that more than one hundred floating net cage compartments have experienced fish mortality. In one plot the losses suffered by farmers reached Rp. 20 million.

The death of the Maninjau lake fish has often happened. The worst incident occurred in 2016. At that time bad weather like strong winds and heavy rain hit this area. As a result, the lake water is wavy which results in the remaining fish food that settles on the lake bottom, rising to the surface of the water. In addition, this Volcanic Lake water also contains sulfur.