Aquaculture is the second-fastest-growing sector in the world after informatics and its. Average growth of aquaculture is annually ~8.8% over the last 30 years. Turkey has great potential in terms of fish production and the number of fish farms started to increase rapidly. Fish production in intensive culture conditions has enlarged possible threats of contagious disease outbreaks due to high stocking densities, water quality or environmental gradient, etc., as well as the combination of all these factors together. Depending on animal husbandry situations and organizational conditions, gradation of the aquatic surroundings and outbreaks of bacteriological diseases may well cause production losses around 30-40% in aquaculture facilities. Some fish diseases reported most repeatedly in Turkish aquaculture facilities are Vibriosis, Furunculosis, Streptococcosis, Lactococcosis, Aeromonas septicemia, Yersiniosis, Photobacteriosis and Flavobacteriosis. Antibiotics, disinfectants and chemotherapeutics used for the prevention and treatment of diseases result in residual antibiotics and chemicals in fish products, microorganisms resistant to antibiotics and damages to the aquatic environment and human health. This situation has led researchers to use alternative feed additives in fish diets such as medicinal plant, herbal extracts, phytochemicals, plant secondary metabolites, immunostimulants and probiotics. This review includes research conducted in Turkey between the years 2001 and 2020, and aims to summarize the findings regarding the use of medicinal plant, herbal extracts, phytochemicals, plant secondary metabolites, immunostimulants and probiotics in fish feed to prevent and treat diseases, improve immunity, increase disease resistance, and reduce stress in fish towards a better management and best aquaculture practice for the sustainability of the growing aquaculture industry in the region and worldwide.