Enrichment of nitrifying microbial communities in aquaculture: current trends and prospects

For the successful management of nitrogenous wastes in aquaculture systems, the enrichment of nitrifying bacterial consortia is of utmost importance. The current review offers a comprehensive overview of the recent developments in the nitrifying bacterial enrichment, underlining their crucial role in maintaining water quality and sustainability for successful aquaculture production. A detailed bibliographic research was conducted using the relevant keywords such as “enrichment of nitrifiers,” “ammonia and nitrite oxidisers,” “ammonia oxidizing archaea,” “comammox,” “bioaugmentation,” “immobilization,” and “application in aquaculture systems” in Pubmed, Scopus, SpringerLink, ScienceDirect, and Google Scholar. Scientific literature was collected from the year 1983 to 2025 and the extracted data were sorted out based on the following criterion. The review analyzed the techniques employed for bacterial enrichment, viz. fed-batch and continuous bioreactor-based approaches along with a relative assessment of various enrichment media. Furthermore, strategic operational parameters such as substrate concentration, pH, temperature, salinity, light exposure, and carbon-to-nitrogen (C/N) ratio, that influence the propagation of nitrifiers, were examined. In addition, the review investigates the possible modes of administration of enriched nitrifiers such as bioaugmentation and immobilization approaches, evaluating their suitability in diverse production systems, viz. zero water exchange ponds, recirculating aquaculture systems (RAS), hatcheries, and biofloc-based operations. In spite of the remarkable innovations, substantial knowledge gaps persist in tracking distinctive nitrifiers from diverse environments, standardizing preservation strategies for enriched nitrifiers, unraveling the ecological significance and functional efficacy of anammox, comammox, archaeal, and probiotic nitrifiers, and successfully incorporating these nitrifiers into scalable and robust aquaculture systems. The review also delineates the vital research guidelines intended at resolving these gaps and progressing the integration of nitrifying microbial consortia into future aquaculture practices.