To limit the use of antibiotics in farmed fish and their potential negative impacts on public health and the environment, an evaluation of “functional alternatives” is required. The availability of effective treatments to control fish diseases is one of the most significant challenges facing aquacultures and veterinarians to reduce consequences of antimicrobial resistance. This paper includes results from in vivo studies in major freshwater-farmed fish species (salmonids, cyprinids, and cichlids), focusing on the efficacy of functional alternatives against Aeromonas spp. infections. It also outlines the recent biocontrol advances and potential alternative treatments in aquaculture. Functional alternative products can increase the resistance against Aeromonas spp. particularly by increasing the immunocompetence of fish. Many diverse alternative products such as probiotics, prebiotics, plants, essential oils, algae phages, minerals, and nanoparticles have been tested, but the diversity of the experimental designs makes it difficult to compare the efficacy of the tested products. It suggests the standardization of investigations on functional feed products for each fish species against a specific pathogen. This review also recommends farm research on functional feed alternatives in natural conditions in order to evaluate the decrease of antibiotic consumption in fish farms.