Citrobacter freundii: a causative agent for ulcer disease in snakehead fish Ophiocephalus argus (Cantor)

Abstract

Ulcer disease has caused significant economic losses in the culture of snakehead fish Ophiocephalus argus (Cantor). Information available on Citrobacter freundii as a possible causal agent for this disease is scarce. In this study, a virulent strain, temporarily named GB1, was isolated from diseased snakehead fish suffering from ulcer disease and was identified as C. freundii through molecular and phenotypic methods. A phylogenetic tree was constructed to examine isolate GB1 and compare it to other known isolates. In addition, isolate GB1 has developed resistance to aminoglycosides, tetracyclines, and sulfonamides drugs for veterinary use in aquaculture as revealed when screened against a range of common antibiotics. To the best of our knowledge, this is the first report of ulcer disease caused by C. freundii in snakehead fish. Published