This document discusses probiotics and their utilization in aquaculture. It begins by providing background on global aquaculture production trends. It then defines probiotics and outlines their history of use, including their first applications in aquaculture in the 1980s. The document discusses the selection and screening of probiotic bacteria, including methods for culture, isolation, and identification. It also examines the functions, attributes, safety aspects and modes of action of probiotics in aquaculture.