Along the Iraqi banks of the Euphrates river, one question dominates the conversation. What killed the fish?

Thousands of tonnes of freshwater carp have washed up dead this month, leaving Iraqi fish farmers reeling from the significant loss of earnings. Carp is the country’s national dish, commonly barbecued outdoors across restaurants in Baghdad.

Agriculture officials have ruled out deliberate poisoning after rumors swirled of unspecified foul play, but the immediate causes are still unclear.

The worst-hit fish farms are in Babel province, south of Baghdad, where farmers scooped dozens of floating carp carcasses out of their cages and dumped them in the Euphrates over the weekend.

“We could not remove them all,” said Mohammed Ali Hamza Al-Jumaili, a fish farm owner in Mussayab, some 70 km (43.5 miles) south of Baghdad. “The effort of a whole year has been wasted in addition to the money we had paid for workers and feed. We have employed more workers to get dead fish out of the cages.”

As excavators were employed to remove the large volume of the dead fish, Al-Jumaili warned that prices could more than double to 10,000 Iraqi dinars ($8.43) per kilo after the losses.

“We call on the government to compensate all the fish farmers, whether those who have officially-licensed farms or those who do not, to enable them to continue fish production. Our losses were huge, as you can see.”

The agriculture ministry said in a statement on Sunday that illness among the carp spread quickly because of cramped conditions in breeding cages, and that reduced water flow along the Euphrates had also contributed.

It said that in the last 48 hours no new cases of perishing fish have been reported. The official Al-Sabah newspaper reported on Sunday that tests would be done outside the country to try to find out what killed the fish.

The incident is a dramatic sign of worsening pollution and water problems in Iraq, which is increasingly struggling to provide a sufficient supply of clean water, especially in the south of the country.

In Basra, some 300 miles (500 km) to the southeast of Baghdad, the Shatt-al-Arab river, where the Euphrates and Tigris meet, is now so polluted it threatens the lives of the more than 4 million inhabitants. (Reuters)