Chronic streptococcosis in Nile tilapia, Oreochromis niloticus (L.), caused by Streptococcus agalactiae

1 Key Laboratory for Aquatic Products Safety Department of the Ministry of Education/State Key Laboratory ofBiocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China2 College of Veterinary Medicine, Hunan Agricultural University, Changsha, Hunan, China3 Guangdong Provincial Aquatic Animal Epidemic Disease Prevention and Control Center, Guangzhou,Guangdong, China4 Aquaculture Technology Service Station of Zhuhai, Zhuhai, Guangdong, China