ISIS suicide bombers devour it as a last supper. Iraqi exiles clamor for it. Such was Saddam Hussein's love of this fishy delicacy that it might have even betrayed his whereabouts to U.S. troops.

For centuries, Iraqis of all stripes, sects and political persuasions have gone to great lengths for masgouf, the country's de facto national dish. From the mountainous Kurdish north to the marshy, largely Shiite Arab south, Iraqis bond over this smoky, belt-busting extravagance, even when they can agree on nothing else.

Dredged from the brackish depths of the Tigris and Euphrates, the Fertile Crescent's two great rivers, the fish is a much-loved fixture of local cuisine. After whacking a large carp to death with a wooden mallet, emptying its guts and then lacing its skin with chunky salt crystals, chefs mount it on an iron spike, ready to be fire-roasted over wood-fueled flames.

But as with so many other things in Iraq right now, not all is well with the country's soul food.

Desperately poor water quality has emptied the rivers of much of their contents, while ISIS's swath of destruction has enveloped dozens of fish farms, further cutting supply. Additionally, low oil prices have humbled Iraq's energy-dependent economy and have pushed masgouf out of many families' reach. At 7,000 to 9,000 dinar ($6 to $8) per kilo in Baghdad, the price has shot up at least 50 percent since 2015.

"Everything is bad, and people can't even eat their favorite foods to help them forget the problems," says Anwar Abdel Hussein Ellawi, a masgouf restaurateur in the capital's Karrada district. "It's really tragic."

It's also been a long time coming.

As far back as the 1980s, the country's waterways have been mired in a slow-moving collapse. The brutal Iran-Iraq war knocked out many riverside sewage treatment plants. And then the international sanctions program, imposed on Iraq after its invasion of Kuwait in 1990, deprived water engineers of many of the parts to fix these facilities.

Amid widespread state indifference to the environment, everyone from farmers to government factory operators dumped their waste into the increasingly murky waters.

The rivers' stocks began to crumble accordingly. Inland fish catch dropped from almost 19,000 tons to 8,000 tons between the mid-1990s and 2001, according to a 2004 United Nations study, the most recent of its kind.

Less hardy fish disappeared altogether. "Every year we had at least one species of fish dying off," says Nabil Musa, the Upper Tigris waterkeeper, part of the international .

Among adherents of the Mandaean faith, a pre-Abrahamic religion which regards the rivers as sacred and whose clerics only eat foods washed in their waters, the deterioration of the fisheries has been particularly traumatic.

"There are barely any fish these days! Maybe 90 percent less than in the 1990s. And what we do catch tastes of oil," says Sheikh Anmar Ayid, a priest at one of Baghdad's Tigris-side Mandaean temples. "So yes, we're getting sick more."

It wasn't, however, until the water quantity began to drop off as well, in large part due to climate change and upstream Turkish and Iranian dam construction, that the crisis really came to a head.

There was not enough fresh water to dilute the toxins. And with a weaker river flow, there was nothing to stop invasive saltwater species from paddling up from the Persian Gulf, throwing the ecosystem even more out of whack.

In the marshes of southern Iraq, the remaining fishermen are locked in a deep web of poverty and self-destructive practices.

"Just a few years ago, our catch was three, maybe four times bigger," says Hassan Al Shaheen, who works a nighttime shift in the Central Marsh, 60 miles north of Basra. "But it's not just the amount of fish, it's the size." Holding up a small sardine, he says: "You can't make masgouf from this."

Desperate to turn a profit, these fishermen have only exacerbated their troubles. Many use electric "stunners," which kill everything within a few meters of their boats, including spawn and tiny bottom feeders. What big bunni, dhakar and shabbutmay have been there are now getting blasted at birth.

Iraq's troubled river fisheries are, of course, far from unique. But unlike in other Middle Eastern countries with ailing river systems, such as Egypt, fishmongers and avid masgouf consumers have few alternatives.

Because of the sanctions, and the consequent difficulties in importing feed, technical parts and knowledge, limited aquaculture did not emerge until recent years. And when it finally did, ISIS destroyed much of it.

From Mosul to Baghdad, the group's fighters trashed dozens of fish farms as they were pushed back, often stealing generators and expensive, hard-to-replace components as they went. Fish production dropped by 80 percent in some places, according to the (RFSAN), a USAID and U.N.-funded organization in Jordan.

Even for those who weren't directly affected by the jihadists' emergence, the ensuing chaos saddled them with a rash of additional problems.

Trade routes to key markets were cut off, and corruption thrived in the security vacuum. Merchants driving fish from the marshes to Baghdad say they usually have to pass through at least six bribe-seeking checkpoints. With already razor-fine profit margins, some have just given up.

Yet, against all odds, masgouf restaurateurs remain hopeful. The dish is part of Iraq's culture, they say, and in the long run, no obstacles will deprive a determined people of their comfort food.

As masgouf goes, so goes Iraq. "It's like our current political and economic problems. Everything is very bad now," says Ellawi, the Karrada chef. "But eventually we will be fine."

Peter Schwartzstein is a Cairo-based journalist, who covers water, agriculture and environmental issues across the Middle East. You can read more of his work , and follow him on Twitter: @pschwartzstein.

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