A gram-negative slender motile and rod-shaped bacterium involved as a causative agent in columnaris disease among freshwater fishes.
Flavobacterium columnare in cultured media showed rhizoid columnar formations with yellow pigmented root-like appearance in colonies which is motile in agar media showing creeping or flexing motion. It has a life cycle composed of vegetative cells, microcysts and the fruiting bodies. It is capable of surviving in sterile river mud that contains sufficient nutrients to preserve viability.
Flavobacterium columnare is an old kind of disease known in warm water fishes which caused high mortality rate particularly in catfish wherein it adhere to the gill tissue forming gill necrosis as well as fin erosion and skin lesions. This bacterium is considered to be part of the bacterial microbiota of freshwater fish and eggs thriving in a healthy carrier harbouring from the previous outbreak of columnaris disease and serves as an infection source for other fishes.
Flavobacterium columnare is implicated as a causative agent in columnaris disease affecting numerous freshwater fishes either cultured or wild. It is distributed worldwide in freshwater reservoir that infects different fish species including goldfish, carp, channel catfish, eel, perch, tilapia and salmon.
Species: Flavobacterium columnare
• Freshwater fishes
• Columnaris disease