Injectable vaccination in Oreochromis niloticus (Linnaeus, 1758) for the prevention of Streptococcosis and Lactococcosis: Description of the technical and operational procedures for successful immunization

This study describes the technical and operational procedures for the injectable vaccination of Oreochromis niloticus to prevent streptococcosis and lactococcosis.An observational study of the vaccination process was conducted at an intensive net-pen aquaculture facility in the state of Maranhão, Brazil.The facility operates a two-phase production system comprising 60 nursery tanks and 260 growout tanks, with a 250-day production cycle and an average annual production of 2,160 metric tons.The health management protocol involved administering an autogenous vaccine containing Streptococcus agalactiae (serotypes Ib and III), Streptococcus dysgalactiae, and Lactococcus petauri to all fish (100%) at 80 days of age and an average body weight of 120 g.The infrastructure, logistical requirements, and management workflow were characterised, including the necessary equipment and supplies.In addition, the pre-vaccination management protocol involving the use of eugenol as a sedative, including the dosage and immersion time, was documented, along with restraint techniques, routes of inoculation, and anatomical injection sites.The study provides a practical description of the structural and operational requirements for implementing intraperitoneal vaccination in the region and serves as a reference for standardising preventive health management practices in tropical fish farming.