What your favorite tilapia is hiding from you

The study found that both wild and farmed tilapia in Kenya harbour various parasites, with wild fish showing a higher infection rate. This discovery raises concerns about public health and fish farming practices.

The discovery was made by researchers from the University of Nairobi’s Faculty of Veterinary Medicine and Egerton University.

Parasites are a natural occurrence in fish, not contamination. They only become a concern when consumers eat raw or lightly preserved fish. The researchers said they collected 111 tilapia fishes from selected farms in Taita Taveta County and Lake Jipe to determine their parasitic loads.

"Out of 111 fish examined, 58 (52.3 per cent) were infected with 212 parasites," they said. "The prevalence of parasitic infections was 68.6 per cent in fish from Lake Jipe and 44.7 per cent in farmed tilapia," they said in a paper published in Aquaculture, Fish and Fisheries.

The parasite species in the fish include Diplostomum, which can cause blindness in people and Acanthocephalus, which can cause intestinal obstruction and inflammation.

The researchers also isolated Euclinostomum, whose infection in people may result in death from asphyxiation.

Their paper is titled, “Parasites of Farmed and Wild Tilapine Fishes From Selected Farms and Lake Jipe in Taita Taveta County, Kenya.”

Other co-authors are from the Norwegian Veterinary Institute, and the International Center for Living Aquatic Resources Management, in Malaysia.

Lead researcher Finnan Ageng'o and his colleagues found that wild tilapia had a greater diversity and intensity of parasitic infections compared to farmed fish.

He said the presence of parasites in fish poses a potential risk to human health, especially when fish is consumed raw or undercooked.

“It is important to educate fish farmers and fishermen on the potential risks of parasitic infections in fish to prevent economic losses. Furthermore, it is crucial that fish be cooked thoroughly prior to consumption to eliminate any parasites present,” he said.

Public health experts emphasise that fish should be cooked at temperatures above 63°C to kill any parasites. Freezing fish at -20°C for at least seven days is another method that can help reduce the risk of parasitic infections.

Ageng'o and his colleagues said fish farmers in Kenya may need to adopt better management practices to reduce parasite infections. "The optimal conditions for parasite proliferation involve factors such as poor water quality, overcrowding, and lack of biosecurity measures," they explained.

 Effective water management, regular health checks, and proper sanitation can help mitigate these risks.

Additionally, the study calls for increased awareness among fish farmers about the impact of parasites on fish health and marketability. "Many farmers are unaware of the negative impacts related to fish diseases and the importance of biosecurity measures for their farms," the researchers said.

The findings highlight the need for continued research into fish parasites in Kenya and the development of targeted strategies to control them. "Understanding parasite distribution in different environments is essential for designing effective interventions," the authors said.

Ageng'o and other colleagues have previously found some of these parasites in farmed tilapia in Bomet, and Kericho counties.

 Other studies have also reported the infestation in Kirinyaga, and Uasin Gishu County.