Cytophaga johnsonae: a putative skin pathogen of juvenile farmed barramundi, Lates calcarifer Bloch

Cytophaga johnsonae, a gliding filamentous Gram‐negative rod, was isolated from diseased farmed juvenile barramundi, Lates calcarifer Bloch. Infected fish had extensive but superficial erosion of the skin, mainly involving the posterior flanks, but also affecting the pectoral fins and lower jaw in some individuals. Minimum inhibitory concentrations of a number of antibacterial agents for C. johnsonae were determined; acriflavine and oxolinic acid inhibited growth between 0.78 and 1.5 μg ml−1, while polymyxin B, trimethoprim and sulphamethazine failed to inhibit growth at 100 μg ml−1.