Fruits and Essential Oils: ‘Good for Humans, Good for Fishes—Revisited’

In the search for aquafeed improvement or potential marine protein and lipid replacements in aquafeed, a variety of plant materials from human and livestock consumption have been tested. Among these materials, fruits and wastes from their processing industries have been tested. Another focus of aquafeed improvement is the addition of essential oils. Often, biomolecular methods are used only as sophisticated success monitoring tools and not to understand the biomolecular response of animals in its entirety or to generate new hypotheses and subsequent experimental approaches. The importance of the gut microbiota is just beginning to be understood, and recent bioinformatics tools suggest that the dietary supplements being tested may promote local intestinal immunity through effects on host–microbial cometabolism. The gut microbial composition can be beneficially modulated not only by dietary prebiotics, but also by essential oil and its major compounds via antivirulence activity, opening a perspective for prophylactic nutrition.