Strategies to enhance tilapia immunity to improve their health in aquaculture

Abstract

Various emerging and re-emerging diseases, such as streptococcosis, tilapia lake virus disease and infectious spleen and kidney necrosis virus disease, have had a significant economic impact on the tilapia industry over the last decade. These diseases have resulted in high levels of morbidity and mortality, production losses and trade restrictions. In the absence of effective husbandry management, disease prevention strategies and appropriate biosecurity measures, infectious diseases will continue to challenge the sustainability of global tilapia aquaculture. Strategies used to reduce the impact of disease include feeding probiotic and prebiotic supplements to enhance tilapia health and to modulate the fish's gut microbiota to improve gut health. Herbal medicines and immunostimulants are also used to enhance immunity to disease, while vaccines are available, or are under development, for a number of economically important pathogens affecting tilapia culture. This review provides an overview of the benefits of enhancing the immune response of tilapia to improve their health, and in turn reduce the levels of pathogens within tilapia farming systems.

Organic acids mitigate Streptococcus agalactiae virulence in Tilapia fish gut primary cells and in a gut infection model

“…Species such as Streptococcus agalactiae , Streptococcus iniae and Streptococcus shiloi , belonging to the Streptococcaceae family, prevail in warm climates and are primary culprits behind septicemia and meningoencephalitis in Tilapia and across other species [ 11 ]. Clinical manifestations of Streptococcal infections in these fish are characterized by aberrant behaviour and erratic swimming patterns, loss of appetite, exophthalmos with ocular haemorrhage, corneal opacity, curvature of the spinal cord, muscular stiffness, and haemorrhagic lesions at the fin bases and meningitis [ 2 , 4 , 5 ].…”

“…Over the past thirty years, Nile Tilapia ( Oreochromis niloticus ) has ascended to the forefront of freshwater aquaculture, reaching a global market valuation of US $7.9 billion as of 2020, being cultivated in more than 120 of different nations [ 1 , 2 ]. The cultivation of Nile Tilapia has transitioned from predominantly extensive farming practices to the proliferation of intensive, commercial aquaculture operations due to a rapid reproductive rates and pronounced solvability [ 3 ].…”

“…This shift has positioned Nile Tilapia farming as one of global aquaculture’s most rapidly expanding sectors [ 4 ]. Currently, Tilapia ranks as the third most prevalent species within aquaculture [ 2 ]. China, Indonesia, Malaysia, the Philippines, Thailand, Egypt, Honduras, Ecuador, and Costa Rica, including African countries have established themselves as leading Tilapia producers on the global market [ 5 – 7 ].…”

“…China, Indonesia, Malaysia, the Philippines, Thailand, Egypt, Honduras, Ecuador, and Costa Rica, including African countries have established themselves as leading Tilapia producers on the global market [ 5 – 7 ]. The volume of Tilapia production witnessed a substantial increase, expanding from 1.0 million tonnes in 2001 to 3.6 million tonnes by 2014 and 4.6 million tonnes in 2019 [ 2 , 6 ]. Currently, Tilapia contributes approximately ≈ 4.8 million metric tons to worldwide food security, serving as a comparatively affordable protein source with premium meat quality [ 3 , 4 ].…”

“…These natural substances offer a promising alternative to conventional antibiotics by targeting the virulence factors of pathogens without contributing to the development of antibiotic resistance, marking a pivotal shift towards more sustainable and less disruptive disease management strategies in aquaculture and other fields. In addition to mitigating bacterial pathogenicity, these natural antimicrobials can strengthen fish’s immune response and disease resilience and may even facilitate improved growth rates [ 2 , 13 – 15 ].…”