Efficacy of mineral oil‐based experimental injection vaccines against Flavobacterium psychrophilum were tested in rainbow trout, Oncorhynchus mykiss (Walbaum), under laboratory and field conditions. The vaccines consisted of formalin‐ or heat‐inactivated whole bacterium cell preparations of two different serotypes (Fd and Th) or a combination of serologically different F. psychrophilum (Fd and/or Th and/or Fp T ;Th). Specific...

Immersion and intraperitoneal vaccination are the two most common and successful methods for vaccination of fish (Holm & Júrgensen 1987; Lillehaug 1989). Effective vaccines and the improvement of environmental conditions have dramatically reduced the amount of antibiotics used in aquaculture in Norway from 48.5 t in 1987 to 1.03 t in 1996. Nevertheless, the labour intensive process of vaccination and the often undesirable side...