Lactic acid bacteria (LAB) in aquaculture: current insights, research gaps, and future directions for sustainability

Rapid expansion of global aquaculture in recent decades has increased production but also amplified risks from pollution, pathogenic microbes, and bacterial infections. These issues have driven widespread antibiotic use, resulting in drug resistance, environmental degradation, and risks to human health. To combat this situation, probiotic bacteria are gaining popularity, and among the diverse group of probiotic candidates, lactic acid bacteria (LAB) have emerged as the most promising ones. Naturally present in fish microbiota, LAB promote health by competitively excluding pathogens, producing antimicrobial compounds (organic acids, hydrogen peroxide, and bacteriocins), strengthening gut barrier integrity, and modulating immune responses. This review establishes the scientific basis for recognizing LAB as safe and effective probiotics in aquaculture. It synthesizes current knowledge on species-specific LAB strains isolated from the gastrointestinal tracts of fish, emphasizing their roles in enhancing growth performance, feed efficiency, and immune responses in both fish and shellfish. The review further highlights the pivotal role of LAB in modern intensive aquaculture systems while identifying existing limitations, key research gaps, and future prospects for their broader application. It compares LAB with other major probiotic groups, outlining their unique advantages, potential risks, and recent technological advancements. By extending insights beyond conventional probiotic use, this review proposes a functional classification framework and explores underexplored mechanisms, demonstrating how the strategic integration of LAB can enhance aquaculture productivity, promote sustainability, and ensure the long-term viability of the industry.