Another fish farm in Taoyuan was confirmed Monday to have been infected with the tilapia lake virus (TiLV), bringing the total number to seven since the virus was first reported in the city on June 13, according to the Council of Agriculture (COA).
All seven infected fish farms are in the city's Guangyin District and within three kilometers of the first infected site, according to the COA.
The city government has ordered inspections of all ponds within a three-kilometer radius of the site.
Once those are completed, farms within a five-kilometer radius of the site and others in neighboring Hsinchu will be checked to ensure the virus has not spread, the COA said.
Although the virus only infects tilapia and there is no risk of it being passed on to humans, it is incurable and is listed as a major infectious disease by the World Organization for Animal Health (OIE), the COA noted.
Were it to spread to other parts of Taiwan, it could jeopardize the country's tilapia industry, which is why the COA also ordered expanded inspections of 12 brood fish farms upstream of Shihmen Reservoir, which did not find any evidence of the disease.
Inspections of two fish farms near a farm in Tainan from which the infected tilapia fry were sourced also came up negative, as did inspections of 147 fish farms within one kilometer of the Tainan farm, according to the COA.
The results indicated that the virus is confined to Taoyuan and has not spread to other parts of Taiwan, the COA said.
The infected farms are banned from transporting any living creatures from their premises for two weeks, the COA said.
The virus was first discovered in Israel in 2009 when up to 70 percent of the wild fish population of a natural lake died.
Taiwan is the sixth country to report the virus, after Colombia, Ecuador, Egypt, Israel and Thailand.