Lee Seong Wei, Martina Irwan Khoo, Ramasamy Harikrishnan, Ümit Acar, Md Eilious Hosain, Mohamad Nor Azra, Ahmad Syazni Kamarudin, Lau Kia Kian, Hadiana, Wendy Wee
Continuous and sustainable aquaculture development is essential to provide affordable protein sources for the global population. Nevertheless, the intensification of fish farming at high stocking density led to chronic crowding stress that could impair the growth performance, immune system, and antioxidant capacity of an aquaculture species. Consequently, the prevalence of disease outbreaks increases, resulting in low aquaculture production. Various countries remain highly dependent on antibiotics and chemotherapies to overcome this problem. Recently, researchers have proposed and developed alternative solutions using environmentally-friendly feed additives, such as probiotics, phytobiotics, and synthetic immune stimulants, to mitigate crowding stress. The feed additives reportedly alleviate crowding stress, promote growth performance, enhance gut microbiota, immune system, and antioxidant capacity, and stimulate disease resistance, contributing to the overall improvement of the health status of aquaculture species and boosting aquaculture production. The application of feed additives in aquafeed has been investigated in various aquaculture species to explore their beneficial effects at optimum doses. The study outcomes illustrated that feed additives in aquafeed are promising in mitigating crowding stress among aquaculture species. Herein, this review paper discussed and summarised the impacts of crowding stress on the growth, immune system, and antioxidant capacity of aquatic animals. In addition, this review highlighted the potential of feed additives such as probiotics, phytobiotics, and synthetic immune stimulants in mitigating crowding stress in aquatic animals. © 2026 Lee Seong Wei et al.
Department of Agricultural Sciences, Faculty of Agro-Based Industry, Universiti Malaysia Kelantan, Jeli Campus, Kelantan, Jeli, 17600, Malaysia; Department of Chemical Pathology, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, Kubang Kerian, Kelantan, 16150, Malaysia; Department of Zoology, Pachaiyappa's College for Men, University of Madras, Tamil Nadu, Kanchipuram, 631 501, India; Bayramiç Vocational School, Department of Forestry, Çanakkale Onsekiz Mart University, Çanakkale, Turkey; Department of Fisheries Industry Engineering, Faculty of Marine Sciences and Technology, Çanakkale Onsekiz Mart University, Çanakkale, Turkey; Fisheries Biotechnology Division, National Institute of Biotechnology, Ganakbari, Ashulia, Savar, Dhaka, 1349, Bangladesh; Institute of Climate Adaptation and Marine Biotechnology (ICAMB), Universiti Malaysia Terengganu (UMT), Terengganu, Kuala Nerus, 21030, Malaysia; Research Center for Marine and Land Bioindustry, Earth Sciences and Maritime Organization, National Research and Innovation Agency (BRIN), Pemenang, 83352, Indonesia; School of Animal Science, Aquatic Science and Environment, Faculty of Bioresources and Food Industry, Universiti Sultan Zainal Abidin, Besut Campus, Besut, Terengganu, 22200, Malaysia; Faculty of Pharmaceutical Sciences, UCSI University Kuala Lumpur Campus, No. 1, Jalan UCSI, UCSI Height, Cheras, Kuala Lumpur, 56000, Malaysia; PSDKU Aquaculture, Faculty of Fisheries and Marine Science, Brawijaya University, Jl. Pringgodani, Kel. Mrican, Kec. Mojoroto., Kediri, 64111, Indonesia; Center for Fundamental and Continuing Education, Universiti Malaysia Terengganu, Terengganu, Kuala Nerus, 21030, Malaysia
