By Allan Mahelo | March 6, 2026
The Kenya Marine and Fisheries Research Institute (KMFRI) has issued an urgent advisory to cage fish farmers operating in Lake Victoria, urging them to reduce or temporarily suspend feeding their fish to prevent possible losses from mass fish deaths.
In a notice released on Thursday, KMFRI Assistant Director Dr. Chrisphine Nyamweya said an early warning monitoring system installed at Dunga Beach detected dangerously low oxygen levels in the lake over the past several days.
According to the institute, dissolved oxygen levels have dropped below 2 mg/l, a critical threshold that can lead to suffocation and death of fish, particularly cultured species such as tilapia.
“The onset of heavy rainfall around Lake Victoria in the past week has triggered significant disturbances in the lake’s water column,” said Dr. Nyamweya. “When oxygen levels fall below the minimum threshold, it becomes lethal for farmed fish species.”
The monitoring system has also recorded fluctuations in the lake’s pH levels, a factor that can negatively affect fish health. Changes in pH may interfere with gill function, reduce feeding activity, and increase the likelihood of disease outbreaks among fish stocks.
KMFRI further cautioned farmers about continuing routine feeding during periods of low oxygen. Uneaten feed and fish waste can worsen the situation as they consume dissolved oxygen during decomposition.
“Reducing feeding helps lower the biological oxygen demand around fish cages,” the institute noted.
To minimize potential losses, KMFRI has advised cage farmers in the Winam Gulf region—including Kisumu, Siaya, Busia, Homa Bay, and Migori counties—to partially harvest fish that are close to market size in order to reduce stocking density and ease pressure on available oxygen in the water.
The warning follows significant losses recorded in recent years, with cage fish farmers losing an estimated KSh1 billion worth of fish in 2024 and 2025 due to sudden mass fish deaths caused by oxygen depletion.
Farmers have also been encouraged to move their cages to areas with better water circulation and to report any fish deaths immediately to KMFRI, the Kenya Fisheries Service, the State Department for the Blue Economy and Fisheries, Beach Management Units (BMUs), or county fisheries officers.
