A live attenuated Edwardsiella ictaluri bacterium lacking a viable gene encoding a functional evpB protein and a method of using the same to protect fish against infection from virulent Edwardsiella ictaluri. The methods and compositions for protecting fish against infection from virulent Edwardsiella ictaluri comprising administering to a fish a therapeutically effective amount of an attenuated Edwardsiella ictaluri bacterium lacking a viable gene encoding a functional protein selected from the group consisting of evpB, fur and hfq. The bacterium may include an insertion and/or deletion mutation in the gene. The fish include catfish, preferably catfish fingerling or a catfish fry. The composition may be delivered via immersion delivery, an injection delivery, an oral delivery, or combinations thereof.
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