Developments in selective breeding for resistance to Aeromonas hydrophila in fish

摘要

Aeromonas hydrophila is a gram-negative, facultatively anaerobic, oxidase-positive bacterium causing a wide range of acute, chronic and covert infections in fish, such as dermal ulceration, fin rot and tail rot, ocular ulcerations, erythrodermatitis,hemorrhagic septicaemia (Fig. 1), red-sore disease, red-rot disease, and scale-protrusion disease. Many freshwater fishes (including Nile tilapia, channel catfish, rainbow trout, catla, rohu, mrigal, catfish, eel, goldfish, Puntius sp., Asian catfish, gizzard shad), a few brackish water species, and some marine fishes are affected. Although A. hydrophila is part of the normal intestinal flora of fish, it can cause severe disease under stress. The disease caused by this bacterium is considered a principal microbial disease called Motile Aeromonad Septicaemia (MAS). Once a disease outbreak occurs, the spread of this type of septicaemia is rapid and can cause high mortality in cultured fishes. Aeromoniasis has also been reported in outbreak forms in intensive carp farms (Mohanty et al. 2008).