Presently, tilapia is ranked among the top ten aquaculture species in terms of both quantity and value. In terms of freshwater fish production in the world, tilapia ranks third, just after silver and grass carp. It is one of the most popular farmed fish in the world as it is farmed in 78 countries, with China ranking first; Egypt is the largest producer of tilapia in Africa and the third internationally, just after Indonesia). The popularity of tilapia is reflected in the data produced by the FAO, according to which, global tilapia aquaculture production has grown from 0.3 million tons in 1987 to 5.9 million tons in 2017.
Tilapia Lake Virus (TiLV ) is a globally emerging virus that leads to mass mortality in cultured and wild tilapia worldwide. The scientific knowledge about TiLV is limited, and many important questions remain unanswered. The virus was first reported from Israel followed by other countries, making it a cross-border animal disease with economically damaging effects.
Although accurate detection methods exist, there is a need for the development of more specific and sensitive diagnostic methods. Also, further studies on the pathogenesis and prognosis of the disease would help in the development of suitable preventive measures. Since farmers associated with tilapia aquaculture belong to lower-income groups, the focus is on developing cost-effective, precise diagnostic methods that do not require extensive laboratory facilities. The development of selectively bred resistant tilapias could also be a way to reduce the mortality rate.
In order to prevent and reduce the spread of the virus, much work is being focused on better screening of live fish transports at national and international borders. Along with this, good operational management practices are necessary, including the application of appropriate biosecurity measures (e.g., the proper use of disinfectants, and the quick removal of moribund and dead fish from affected ponds). In addition, since stress factors in fish play a major role in the severity of virus outbreaks, they should be reduced through appropriate management measures.
Currently, commercial vaccines are not available for TiLV prevention; however, research is ongoing to develop an effective and affordable vaccine. In addition, improved exchange of information or extensive studies on the factors associated with the field outbreaks, such as the water temperature, the pond used, the water parameters, agricultural practices, and the transport of live fish, are helpful as this could lead to appropriate control measures.