A Pseudomonas associated with disease in cultured rabbitfish Siganus rivulatus in the Red Sea

Abstract

Experiments were carried out to study the cause of a disease outbreak among rabbitfish Sjganus rivulatus in the Saudi Arabian mariculture facility in the Red Sea and to investigate means of protecting fish against the disease. The causal agent of the disease proved to be a bacterium that was identified as Pseudomonas putrefaciens. When the bacterium was injected into healthy fish, it resulted in high mortality and produced the same clinical signs as those observed during the disease outbreak. A bacterin prepared by formalin killing was used to vaccinate fish. Fish vaccinated once by intraperitoneal Injection suffered 17 % less mortality than control fish when challenged with the hon~ologous bac-terlum. Fish vaccinated twice by the same method suffered 40 % less mortality than control fish. Fish were also vaccinated by direct immersion in the bacterin but when these fish and their unvaccinated counterparts were challenged by dipping into a suspension of the homologous bacterium they did not show any clinical signs nor did any mortality occur The disease was thought to b e stress-related.