Carnobacterium piscicola CP5 produced a bacteriocin named carnocin CP5 that inhibited Carnobacterium, Enterococcus and Listeria spp. and among the Lactobacillus spp. only Lactobacillus delbrueckii ssp.. Carnocin CP5 was stable 1 h at 100°C at pH 7.0. It was inactivated by numerous proteolytic enzymes. Production of carnocin CP5 occured in MRS broth regulated at pH 7.0. The apparent molecular weight of the bacteriocin in the crude extract was greater than 10 kDa, but around 5 kDa after action of SDS or urea. Novobiocin treatment led to non-producer variants.