Bacteria capable of producing fruity and onion-like odours have been isolated from Atlantic cod and haddock fillets that had developed off-odours of this type. These organisms have been identified as being non-proteolytic strains ofPseudomonas fragi.Compared to other fish-spoiling bacteria, including cultures ofSerratia,Proteus,Achromobacter, and green pigmentedPseudomonas,Ps.fragiis quite sensitive to the bacteriostatic action of antibiotics of the tetracycline group.