Why Fish Are Dying in Lake Valencia

CARACAS, June 19, 2025

The sudden death of fish in Lake Valencia is alarming communities, with lifeless fish seen since June 13.

A natural process, worsened by the lake’s poor water quality, is likely the cause of the fish deaths.

• Mass fish deaths have been reported in Lake Valencia since June 13.
• The phenomenon is linked to the lake’s eutrophic state and poor water quality.
• Local authorities have inspected the affected areas but have yet to provide an official explanation.

The ongoing crisis in Lake Valencia, where numerous dead fish are appearing, is due to a natural process accelerated by the lake’s poor water quality.

Residents of Isla La Culebra in the Los Guayos municipality, along with areas of Carlos Arvelo and Guacara, have reported the distressing sight of hundreds of dead fish floating or stranded along the banks.

Biologist and limnologist Ernesto gonzález Rivas, a professor at the Central University of Venezuela (UCV), explained that this type of event is common in eutrophic ecosystems like Lake Valencia. These ecosystems are overloaded with nutrients such as nitrogen and phosphorus, frequently enough from domestic, agricultural, and industrial wastewater.

“In these lakes there is a high biological productivity. Microalgae and cyanobacteria do photosynthesis and produce oxygen on the surface, but at the bottom of the lake organic matter accumulates that decomposes and consumes that oxygen. When the water is mixed by wind action, these conditions are homogenized and the oxygen decreases throughout the water column, causing the death of fish by foil,” stated Gonzalez.

Did you know? Eutrophication can also lead to harmful algal blooms, some of wich produce toxins that are hazardous to humans and animals.

A Trapped Lake and Rising Pollution

Lake Valencia faces a critical problem: it’s an endorheic basin, meaning it has no natural outlet. Consequently, everything that enters the lake, from sewage to agricultural waste, remains trapped, accumulating over time and leading to eutrophication.

The biologist noted that the winds in the region,particularly between November and April,facilitate the mixing of the lake’s waters,equalizing conditions throughout. This process, in a lake already laden with nutrients and organic matter, spreads areas of low oxygen, directly impacting the survival of fish.

González explained that this phenomenon isn’t new, having been documented since 1970 by Professor Aída González Infante in a Venezuelan scientific publication. The publication documented similar incidents of mass fish mortality in Lake Valencia, with photographs illustrating the current situation: shores covered in dead fish and an unpleasant environmental odor.

Reader question: what actions do you think are most crucial for addressing the pollution in Lake Valencia? Share your thoughts in the comments below.

What’s Happening Now in Lake Valencia?

According to residents, dead fish began appearing on Isla La Culebra on Friday, June 13, specifically near the embankment connecting the community with surrounding areas. The problem quickly expanded to the riverside areas of Carlos Arvelo and Guacara, suggesting a widespread pattern across the lake.

The stench is now reportedly unbearable, and the decaying fish could pose a health risk. Local authorities, along with firefighters and civil protection, have inspected the area but have yet to provide an official explanation for the cause or any possible mitigation measures.

González Rivas believes that the situation may begin to improve in the coming weeks. With the arrival of the rains, the wind decreases and the waters of the lake are stratified again. This allows algae to perform photosynthesis on the surface and, gradually, oxygen returns to more acceptable levels in areas where fish inhabit.

A Recurring Cycle Without Addressing the Root Cause

While the fish deaths are a natural process in eutrophied lakes, the scale of the problem is directly linked to pollution. as untreated sewage and waste laden with fertilizers continue to enter the lake, the cycle will repeat frequently. “Not necessarily every year occurs mass deaths, but with some regularity,” the expert warns.

This situation causes a serious problem for riverside communities,who must endure foul smells and witness the decline of aquatic life. These communities now demand action from the relevant authorities. The situation also highlights the urgent need for sustainable environmental policies and a complete sanitation plan for Lake Valencia.

For years, the scientific community has emphasized the need to regulate sewage discharge, clean the ravines flowing into the lake, and control the use of agrochemicals in nearby agricultural areas. Without these actions, eutrophication will continue to worsen, and each mixing of the waters will pose a threat to the lake’s biodiversity.

Local Demands for Solutions and Environmental Monitoring

The residents of Isla La Culebra and other affected communities have yet to receive clear details or immediate action from officials. They fear that the decaying fish will increase the risk of diseases and further environmental damage, and are therefore urging the environmental authorities of the Carabobo State and the Ministry of Ecosocialism to act promptly.

The current situation in Lake Valencia is more than just an emergency; it is a reflection of decades of environmental neglect. The problem has been repeating for over 40 years, documented and consistently affecting the lakeside communities of the country’s second-largest lake.

The solution requires more than just removing dead fish; it requires restoring the lake, stopping pollution, and ensuring that the residents of Carabobo can live without fear of ecological crises.

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Beyond the Surface: A Deeper Dive into Lake Valencia’s Plight

The recurring mass fish deaths in Lake valencia, detailed since June 13, highlight the complex interplay of natural processes and human impact [[1]]. The lake’s eutrophic state, worsened by pollution, creates a dangerous environment for aquatic life. But what are the broader implications of this environmental crisis, and what lessons can be learned?

Understanding the root causes is crucial.Eutrophication, the over-enrichment of water bodies with nutrients like nitrogen and phosphorus, is at the heart of the problem. These nutrients, frequently enough from untreated sewage, agricultural runoff, and industrial waste, fuel excessive algae growth – triggering a cascade of destructive consequences.

The Domino Effect: How Eutrophication Kills

The process unfolds in a predictable, yet devastating sequence:

1. Algae Blooms: Increased nutrients cause accelerated growth of algae and cyanobacteria.
2. Oxygen Depletion: As these organisms die, they sink to the bottom. Decomposition by bacteria consumes vast amounts of oxygen,creating “dead zones.”
3. fish Suffocation: Fish and other aquatic life suffocate due to the lack of oxygen.
4. Ecological Imbalance: The loss of fish disrupts the entire food web, impacting other species.

The situation in Lake Valencia is further elaborate by its status as an endorheic basin. Because it has no natural outflow, pollutants accumulate. this makes the lake exceptionally vulnerable to eutrophication and amplifies the effects of any pollution input.

Beyond Fish Kills: Broader Environmental and Health Risks

The immediate impact – the sight and smell of dead fish – is only the most visible sign of a larger problem.The decaying fish can contaminate the water and pose meaningful health risks to local communities.

Beyond the immediate smell and the environmental damage, there are long-term issues facing the ecosystem surrounding Lake Valencia. According to experts, eutrophication, when it creates imbalances in the water column can cause algae blooms, which also produce