The gastrointestinal tract of fish -- Immune defences of teleost fish -- Gastrointestinal pathogenesis aquatic animals -- The gut microbiota of fish -- Methodological approaches used to assess fish gastrointestinal communities -- Indigenous lactic acid bacteria in fish and crustaceans -- Probiotics and prebiotics : concepts, definitions and history -- Probiotic modulation of the gut microbiota of fish -- Probiotic applications in cold water fish species -- Probiotic applications in temperate and warm water fish species -- Probiotic applications in crustaceans -- Can probiotic affect reproductive processes of aquatic animals? -- Issues with industrial probiotic scale-up -- Prebiotics in finfish : an update -- Prebiotic applications in shellfish -- Live feeds : mibrobial assemblages, probiotics and prebiotics