In a shriveled side channel of the Danube River in northern Serbia, small boats sit idle on cracked ground as extreme drought and heat have pushed the water back into a couple of shrinking ponds. Fish circle in the shallow water that remains.

"This is all we have, these two little ponds that are full of juvenile fish," said fisherman Dusan Jovanovic. The fish are in danger, he explained, because there is too little water and its temperature exceeds 30 degrees Celsius (86 degrees Fahrenheit).

"If they start to die, they will all die at once," Jovanovic said.

Persistent drought and scorching heat this summer have ravaged ecosystems and businesses across the region — from a lake in Slovenia and the Danube side channel in Serbia to fish farms in Bosnia, the Czech Republic, Romania, and Hungary. The region has experienced recurring heat and drought episodes in recent years, and scientists have linked the growing frequency and intensity of such extreme weather events to human-induced climate change.

The fish industry has been hit especially hard, with damage estimated in the millions of euros (dollars). Pond-based aquaculture, a tradition in Central and Eastern Europe dating back centuries, depends on steady water supplies and is particularly exposed when rainfall fails during summer. The losses add to an already heavy toll from problems with energy and water supplies, devastated crops, and reduced river traffic and trade — low river levels on waterways such as the Danube have repeatedly hampered shipping in recent summers.

Caught unprepared for this year's crisis, countries and businesses are now weighing how to limit the effects of future extreme weather events, a challenge that includes questions about how water is shared between farming and fisheries during shortages.

Hungary: Drought Across Nearly the Entire Country

Around 99% of Hungary's land is currently under severe or extreme drought conditions, according to the national meteorological service. Desertification — the process by which vegetation recedes under high heat and low rainfall — threatens much of the Great Hungarian Plain.

Among the hardest hit are Hungary's roughly 27,000 hectares (67,000 acres) of fish ponds. The country's Agriculture and Food Economy Ministry said last week that "persistent heat and water shortages" had caused 1,588 hectares (3,924 acres) of those ponds to dry out, killing nearly 280 metric tons of fish at 20 farms.

The estimated revenue loss from the damage was 1.3 billion forints ($4.2 million), the ministry said. Producers say replacing the lost fish could take years. The Hungarian Aquaculture and Fisheries Inter-branch Organization said in early August that operators were sometimes forced to drain one pond and divert its water to save fish in another.

Romania: Cumulative Losses From Repeated Droughts

For Romanian fish farmers, particularly those cultivating carp, this year's blistering heatwave follows severe droughts in 2023 and 2024 whose effects are still being felt, said Catalin Platon, president of the ROMFISH National Association of Fish Producers.

In carp production, the production cycle runs three or four years, Platon noted, which means a single bad year can weigh on output well into the future.

"So what we lost in 2023 has (had an) impact every year since," he explained. Water-use policies that prioritized agricultural irrigation during previous droughts "left us with no water for the fish," Platon complained.

Czech Republic: Emergency Measures on the Ponds

Fish farmers across the Czech Republic have adopted a range of emergency measures: reducing or suspending feeding to cut oxygen use, aerating ponds, or draining them when necessary. Warmer water holds less dissolved oxygen, which is why heatwaves strain pond fisheries even before the water disappears.

Officials from the Czech Fishing Association say sustained rainfall could ease the immediate crisis, but long-term measures are needed to retain more water in the landscape.

Jan Sokolik, a technician at the Rybarstvi Trebon fishery, explained that "some ponds that were actually low on water have already been fished, but they were all marginal ponds."

"Now we're just starting to plan what to do with the big ponds," he said.

Bosnia: Trout Farms Struggle to Survive

Veljko Budjen owns a trout farm near Trebinje in southeast Bosnia. Hot, dry summers have created serious problems in the mainly mountainous country, which is famous for its trout restaurants.

"Trout is a cold water fish, which requires cold water with a lot of oxygen," he said. "So during the summer you are forced to reduce trout production and feeding so the business can just barely survive."

One option, he said, is to add liquid oxygen to the water during the summer months. Otherwise, "you wait for the first rain."

Slovenia: Pumping Water Into a Suffocating Lake

Emergency teams have been pumping water into Lake Pristava in eastern Slovenia, a favorite spot for fishermen, to try to prevent a mass fish suffocation caused by oxygen depletion and water chestnut overgrowing across the lake surface.

Firefighters have pumped in 8 million liters (2 million gallons) of water, but they still fear it is not enough.

"We are surprised that any fish has survived at all," Danijel Fras of the Pesnica Lenart Fishing Association told public broadcaster RTV Slovenia.

Serbia: Relocating Fish From the Danube

In Serbia, fishermen said the only solution for the endangered fish in the Danube side channel at Novi Sad is to move them to another location.

"The temperatures this year are extreme," Jovanovic said. "No one can remember anything like this."

This story was originally featured on Fortune.com.