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Troubled Waters: Jakarta Battles Deadly, Invasive Suckerfish

The sapu-sapu was introduced to Indonesia from South America, brought in to keep aquariums algae free but chucked into rivers as they outgrew their tanks. BAY ISMOYO / AFP
The sapu-sapu was introduced to Indonesia from South America, brought in to keep aquariums algae free but chucked into rivers as they outgrew their tanks. BAY ISMOYO / AFP
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Troubled Waters: Jakarta Battles Deadly, Invasive Suckerfish

The sapu-sapu was introduced to Indonesia from South America, brought in to keep aquariums algae free but chucked into rivers as they outgrew their tanks. BAY ISMOYO / AFP
The sapu-sapu was introduced to Indonesia from South America, brought in to keep aquariums algae free but chucked into rivers as they outgrew their tanks. BAY ISMOYO / AFP

Mounds of slimey carcasses pile up on a riverbank in Jakarta where authorities are fighting an uphill battle against a fast-breeding invasive fish flourishing in Java island's heavily polluted waterways.

The sapu-sapu, a sucking fish introduced from South America decades ago to keep Southeast Asian aquariums algae-free, has made a home in Javan rivers, many after being thrown out for outgrowing their tanks.

Unlike in the Amazon River where it has natural predators, the sapu-sapu quickly took over in Java, outbreeding indigenous freshwater fish, eating their eggs and outcompeting them for food.

Residents and campaigners have complained about the stinky, unsightly pileups of fishy remains, and the potential health risk for those who consume snacks made from polluted sapu-sapu stock.

Invasive species are spreading ever faster across the globe and cost well over $400 billion a year in damages and lost income, according to a 2023 United Nations assessment.

Surprisingly adept at living in polluted water, the sapu-sapu -- also known as suckermouth catfish, janitor fish or pleco -- can grow to half a meter (20 inches) in length and a female can lay thousands of eggs every year.

"That there are thousands of (sapu-sapu) fish in some of these river bodies, where, you know, the rivers are like dark black, almost smelling like rotten eggs... is completely crazy," clean river campaigner Gary Bencheghib told AFP.

Killing sapu-sapu is not addressing the real problem, he added in a phone interview, nearly halfway through a 1,200-kilometer (746-mile) run from Bali to Jakarta to raise money for river cleanups and having witnessed the crisis at several stops along the way.

The real solution is cleaning up "the waste it lives off... that you find in these polluted waters," said Bencheghib, co-founder of the Sungai Watch NGO.

- 'A dangerous snack' -

More than half of Indonesia's rivers are heavily polluted, and two of the country's major river systems are among the dirtiest in the world, according to data from the UN Environment Program.

Nationwide, only about 7.4 percent of municipal wastewater is safely collected and treated.

Greater Jakarta, a water-stressed metropolis of 42 million people, is particularly affected.

But sapu-sapu are able to live in oxygen-poor and polluted waters, digging holes into riverbanks to lay their eggs and weakening walls that have been known to collapse as a result.

In recent weeks, Jakarta has embarked on a killing campaign involving residents, sanitation workers, fisheries ministry workers and even soldiers.

In two weeks, about 5.3 tons of the fish have been removed from rivers in South Jakarta alone, mayor Muhammad Anwar told AFP while overseeing an operation at Babakan Lake this week.

The sapu-sapu are caught in nets, separated from indigenous fish that are thrown back, then decapitated to make sure they are dead, and buried in mass graves.

Some activists have criticized the procedure as wasteful, arguing the skin could be used for fish leather products and the rest processed into fertilizer or animal feed.

But others say the fish are too contaminated to be useful, and definitely not fit for human consumption.

"It contains... heavy metals and is dangerous to humans," Anwar said.

Tests conducted for scientific studies have found traces of lead and mercury as well as E.coli bacteria beyond safe levels in sapu-sapu.

"In some places, it is consumed as a dangerous snack called siomay (steamed fish dumpling) and pempek (fish cakes)," the mayor said.

"Please be careful when buying fish cakes. Don't be led by the (cheap) price."

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Varieties

Secret Cameras, Mics and AI Reveal Rare Cambodia Wildlife

Hidden microphones, cameras and artificial intelligence to reveal the secrets of species living deep in Cambodia's Cardamom Mountains. TANG CHHIN Sothy / AFP
Hidden microphones, cameras and artificial intelligence to reveal the secrets of species living deep in Cambodia's Cardamom Mountains. TANG CHHIN Sothy / AFP
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Secret Cameras, Mics and AI Reveal Rare Cambodia Wildlife

Hidden microphones, cameras and artificial intelligence to reveal the secrets of species living deep in Cambodia's Cardamom Mountains. TANG CHHIN Sothy / AFP
Hidden microphones, cameras and artificial intelligence to reveal the secrets of species living deep in Cambodia's Cardamom Mountains. TANG CHHIN Sothy / AFP

Above the patter of rain cascading through the jungle canopy comes the haunting call of a pileated gibbon singing to fend off intruders in Cambodia's Cardamom Mountains.

It is being recorded as part of work harnessing hidden microphones, cameras and artificial intelligence to reveal the secrets of species living deep in the rainforest and help protect them.

To conservationist Ratha Sor, the whoops and whistles are the sound of hope -- a sign that the country's largest remaining stretch of intact rainforest is healthy enough to support the endangered species, said AFP.

Gibbons are "indicators that our forest is still alive", he said.

By showing that everything from pangolins to elephants call the Cardamom Mountains home, conservationists hope to secure its future, in a country that has lost over a third of its forest cover in the last 25 years.

"This is the real evidence... we are conserving very unique species in our landscape," said Ratha Sor, biodiversity and science manager at Conservation International (CI), a US-headquartered non-profit.

The Cardamoms range, spread across more than a million hectares (2.47 million acres) in southwest Cambodia, is regarded as one of the most important remaining rainforests in the region.

For decades, it was eaten away by rampant deforestation and emptied by poaching.

Bolstered protections have helped slow both, though infrastructure projects, including dams, remain a serious threat.

In 2024, CI published the results of the first-ever systematic camera trap survey of the Central Cardamom region, revealing more than 100 resident species, nearly two dozen of them either vulnerable or endangered.

That effort, involving nearly 150 devices placed at regular intervals, will be repeated later this year.

It is supplemented by ongoing targeted camera trapping, focused on areas where animals are likely to be and offering deeper understanding of how populations are changing and behaving.

- Macaques, dholes, elephants -

AFP joined conservationists, rangers and locals this month as they retrieved and replaced cameras and microphones in the forest.

Under a chaotic canopy woven with vines and studded with fearsome spiked stems, the group crossed streams, waded through mud and picked off dozens of leeches.

Local community members like Pan Sok, a member of the Chong Indigenous minority, guide CI on where to place devices.

The 50-year-old lives outside the forest but calls himself a "jungle man" after years tapping resin from its trees.

He sat to review black-and-white footage from a camera he helped locate, describing "pride" at the sight of pig-tailed macaques, endangered wild dogs called dholes and his favorite, elephants.

"My efforts paid off," said Pan Sok.

Some of these species are seen fairly regularly elsewhere in Southeast Asia, but encounters can be vanishingly rare in the Cardamoms.

A ranger told AFP he had not seen an elephant once in 12 years patrolling.

While camera traps can capture many of the forest's inhabitants, gibbons are rarely seen because they live in treetops and move too quickly, so CI is turning to bioacoustic monitors and AI.

Its staff spent three months training a machine-learning program to identify calls recorded by dozens of monitors placed at 10 sites.

They are set at least three kilometers (1.9 miles) apart, as close as gibbon groups come to each other without fighting, meaning each device is picking up a different troop.

- 'This is gibbon, this is not' -

In just six weeks, the monitors recorded nearly 800 calls.

The team labelled up to half the data for the AI, teaching it "this is gibbon, this is not", said Ratha Sor.

AI then processed the rest, and in the future will be trained to distinguish male from female, and eventually individual calls.

Experts say poaching in the region has waned, though a ranger found part of an old snare during AFP's visit.

Patrolling has also reduced small-scale encroachments, but infrastructure projects including multiple dams are still driving deforestation.

In the last five years, the Central Cardamom protected region has lost nearly 7,000 hectares of tree cover, Global Forest Watch data shows.

Ratha Sor trod carefully when asked about government-backed infrastructure projects responsible for some of that deforestation.

"It's out of our control," he said.

But he hopes evidence of the region's rich wildlife will show the benefits of leaving the forest standing.

"It is an encouragement to protect... one of the very pristine evergreen forests in this Cardamom Mountains."

Varieties

‘Fingerprints’ of Black Hole’s Event Horizon Detected for First Time

An actual image of the black hole where scientists looked for a ring of light, which is matter and radiation circling at extreme speeds around a region of darkness representing the black hole. (Event Horizon Telescope collaboration)
An actual image of the black hole where scientists looked for a ring of light, which is matter and radiation circling at extreme speeds around a region of darkness representing the black hole. (Event Horizon Telescope collaboration)
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‘Fingerprints’ of Black Hole’s Event Horizon Detected for First Time

An actual image of the black hole where scientists looked for a ring of light, which is matter and radiation circling at extreme speeds around a region of darkness representing the black hole. (Event Horizon Telescope collaboration)
An actual image of the black hole where scientists looked for a ring of light, which is matter and radiation circling at extreme speeds around a region of darkness representing the black hole. (Event Horizon Telescope collaboration)

Scientists have detected the "fingerprints" of a black hole's event horizon -- the boundary from which nothing can escape -- for the first time, according to research published on Wednesday.

The discovery was made by studying ripples in space-time called gravitational waves that were created when two black holes violently smashed into each other.

A black hole's event horizon is known as the "point of no return" because not even light can avoid being swallowed into its darkness.

This has made them incredibly difficult to learn anything about.

However, there is one event of such cataclysmic violence that it could offer a chance to glimpse this extreme phenomenon -- when two black holes merge into one.

When this cosmic death spiral occurs, it shoots gravitational waves across the universe which scientists have been detecting for the last decade.

For the new research published in Nature, an international team of researchers analyzed data from the strongest gravitational wave ever recorded, known as GW250114, detected by the LIGO observatory in January 2025.

By isolating the last burst of waves -- known as "direct waves" -- from this black hole merger, the scientists said they were able to extract information from closer to an event horizon than ever before.

"This black hole horizon concept normally appears in science fiction," lead study author Sizheng Ma of the Perimeter Institute for Theoretical Physics in Canada told AFP.

"But now we are really able to touch the region around the horizon with gravitational data," he added.

"Sometimes I cannot believe this is really happening."

- Causing a stir -

The last stage of two black holes merging is like a spoon stirring a glass of water, Sizheng Ma explained.

The resulting swirl in space creates the ripple of gravitational waves that travel at the speed of light in all directions.

If the metaphorical spoon is stirring close enough to the black hole's event horizon, "this offers us a chance to decode the physics around that region", Sizheng Ma said.

By supporting the theory of general relativity, the results "proved that Einstein was correct again," he added.

The scientists emphasized that more research was needed to decipher what can be gleaned about event horizons using this method.

But they did detect information about how black holes twist space around themselves as they rotate -- a phenomenon known as "frame dragging".

"This is similar to pushing a glass into a table and twisting it, so that the tablecloth winds up around it," Maximiliano Isi, a gravitational wave astrophysicist at Columbia University, told AFP.

In the future, the team of scientists hope to find signs of tiny changes known as quantum fluctuation.

"In this way, we can really probe this near horizon region to look for a new physics," including searching for a deviation from general relativity, Sizheng Ma said.

- Reaction mixed -

Experts not involved in the study urged caution.

Francesco Sannino, an Italian theoretical physicist who studies black holes, told AFP it was "compelling analysis" but needed to be checked by other researchers.

Still, it was "striking" that the scientists were able to show that gravitational waves carried the event horizon's "fingerprints," he said.

The astrophysicist Isi described the work as "tantalizing".

"More generally, understanding the physics of black holes and their mergers is important as it might shed light on how space and time are woven together at a more fundamental level," he told AFP.

Sean McWilliams, an astrophysicist at West Virginia University, was skeptical that the gravitational wave frequency analyzed by the scientists was actually "dictated" by the event horizon.

For this reason, "the actual observed signal doesn't really tell us anything about the horizon or the other properties directly related to it", he told AFP.

Sizheng Ma said McWilliams's statement was "not correct," suggesting he had conflated two different aspects in the paper.

"There is often considerable resistance and criticism in the early stages of promoting a new concept," he said, adding he is working on another paper to "clarify these confusions and possible misinterpretations".

Varieties

Asteroid Zooming Past Earth on Saturday Visible to Stargazers

FILE PHOTO: A nighttime view of Earth, derived from satellite images taken daily over the past decade, capturing human activity on the planet through the emissions of artificial light, is seen in this image released on April 8, 2026. Michala Garrison/NASA Earth Observatory/Handout via REUTERS
FILE PHOTO: A nighttime view of Earth, derived from satellite images taken daily over the past decade, capturing human activity on the planet through the emissions of artificial light, is seen in this image released on April 8, 2026. Michala Garrison/NASA Earth Observatory/Handout via REUTERS
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Asteroid Zooming Past Earth on Saturday Visible to Stargazers

FILE PHOTO: A nighttime view of Earth, derived from satellite images taken daily over the past decade, capturing human activity on the planet through the emissions of artificial light, is seen in this image released on April 8, 2026. Michala Garrison/NASA Earth Observatory/Handout via REUTERS
FILE PHOTO: A nighttime view of Earth, derived from satellite images taken daily over the past decade, capturing human activity on the planet through the emissions of artificial light, is seen in this image released on April 8, 2026. Michala Garrison/NASA Earth Observatory/Handout via REUTERS

A large asteroid that will zoom harmlessly past Earth on Saturday will be visible to stargazers using a small telescope or large binoculars, the European Space Agency announced Wednesday.

The asteroid will come within 2,560,000 kilometers of Earth at 1114 GMT on Saturday, which is more than six times the distance between the Earth and the Moon.

Called (152637) 1997 NC1, the asteroid will be speeding along at nearly nine kilometers a second, posing no threat to Earth as any chance of an impact has been ruled out.

Discovered in 1997, the asteroid is estimated to be between 750 and 1,650 meters wide, according to calculations based on how much sunlight it reflects.

However other estimates suggest it could be smaller, AFP quoted the ESA as saying in a statement.

"A close approach to Earth by an object this size only occurs every few years, although this time the bright nearby Moon might impede its observability at closest approach," Juan Luis Cano of the ESA's Planetary Defense Office said in a statement.

For stargazers with telescopes or binoculars, the asteroid will be visible in parts of the Northern Hemisphere as it approaches, almost everywhere as it speeds past Earth, and only from the Southern Hemisphere as it departs.

But this depends if people are in areas of the world where the sky is dark enough as it passes.