Bacterial disease outbreaks remain a primary threat to the global aquaculture sector, which reached a production value of US$296.5 billion in 2023. With annual economic losses from disease exceeding US$6 billion, and increasing regulatory restrictions on antibiotics in the UK, EU and China, the search for sustainable growth promoters has intensified.
A recent study conducted by researchers at Nanyang Technological University and the University of New South Wales has suggested that the answer may lie in a synergistic blend of “good” bacteria and a common kitchen spice. They investigated the effects of co-administering encapsulated probiotics and curcumin (the active compound in turmeric) on Asian seabass (Lates calcarifer) fingerlings.
The researchers found that this dual-action strategy not only accelerated growth but also provided a robust shield against common aquatic pathogens like Streptococcus iniae and Vibrio parahaemolyticus.
Optimising delivery through encapsulation
A critical challenge in using probiotics in commercial fish feed is ensuring the live bacteria survive the harsh conditions of the fish’s digestive tract, as well as the high temperatures of the feed manufacturing process. To solve this, the team used a patented spray-drying technique to wrap the probiotic strain Lactiplantibacillus plantarum in an alginate-based protective shell.
This encapsulation acted as a shield against gastric acids. While ‘free’ or unencapsulated probiotics showed a complete loss of viability when exposed to simulated stomach acid, the encapsulated versions maintained high survival rates. This ensured that the beneficial microbes reached the intestine intact, where they could colonise the gut and improve nutrient absorption.
At the same time, the microparticles (measuring less than 10 micrometres) were small enough to be mixed into standard feed pellets without affecting the taste or palatability for the fish.
Synergistic effects on growth and efficiency
The researchers conducted a 28-week feeding trial comparing five different diets: encapsulated probiotics (EP), free curcumin (FC), a combination of free probiotics and curcumin (FPFC), a combination of encapsulated probiotics and curcumin (EPFC), and a standard control diet. The results showed a marked improvement in productivity across all functional feed groups.
Fish fed with the encapsulated probiotic diet (EP) showed the most dramatic growth, with a 33% increase in body weight compared to the control group. The curcumin-only group also performed well, seeing a 26.5% rise in weight. Furthermore, all experimental groups showed better feed conversion ratios (FCR), meaning the fish were more efficient at turning feed into muscle, a key metric for profitability in commercial fish farming.
The researchers noted that the combination of these two ingredients created a “functional performance” that exceeded individual treatments. By modulating the gut microbiota and enhancing digestive enzyme activity, the probiotics helped the fish extract more energy from their food, while curcumin’s antioxidant properties reduced the metabolic stress that often slows down growth in intensive farming environments.
Strengthening disease resistance
Beyond growth, the study focused on the “disease resilience” of the fingerlings when challenged with lethal doses of bacteria. In the aquaculture industry, Vibrio and Streptococcus are responsible for approximately USD 1 billion in annual losses. The trial results indicated that curcumin is a powerhouse for immune priming.
In the challenge against Vibrio parahaemolyticus, the groups fed with free curcumin (FC) and the encapsulated combination (EPFC) achieved a 100% survival rate, whereas the control group suffered 50% mortality. When faced with Streptococcus iniae, the combination diets again outperformed the rest, with the FPFC group reaching total survival.
The study suggested that while probiotics focused on gut health and growth, curcumin acted as a systemic immunomodulator. It elevated the activity of antioxidant enzymes and strengthened the intestinal barrier, making it harder for pathogens to invade the fish’s tissues. The authors explained that this “immune priming” prepared the fish’s natural defences to react more quickly when an actual infection occurred.
A sustainable path forward for aquaculture
The implications for the aquaculture supply chain are significant. As the industry moves away from prophylactic antibiotic use due to the risk of antimicrobial resistance (AMR), functional feeds could offer a “responsible aquaculture” solution that meets both regulatory requirements and consumer demand for cleaner seafood.
The researchers emphasised that the spray-drying encapsulation method was scalable and cost-effective for feed manufacturers. By using natural bioactive compounds like curcumin, which is already widely available and safe for consumption, producers can create high-value feeds that reduce the waste associated with fish mortality and poor feed efficiency.
While the laboratory results were compelling, the team also acknowledged that the next step was validation in large-scale, commercial aquaculture settings. Future research will likely focus on refining the dosages for different species and life stages, as well as evaluating the long-term economic feasibility of adding these high-spec ingredients to bulk feed orders.
For now, the combination of encapsulated probiotics and curcumin stands as a promising, natural platform to enhance the productivity and resilience of the global fish farming industry. The researchers concluded: “Overall, these findings demonstrate the potential of curcumin-probiotic functional feeds as a sustainable alternative to antibiotics, providing a scalable strategy to improve fish health, productivity, and resilience while supporting responsible aquaculture practices.”
Source: Journal of Animal Science and Biotechnology
“Combinatorial supplementation of fish feeds enhanced growth performance and disease resilience in aquaculture”
https://doi.org/10.1186/s40104-026-01357-3
Authors: The‑Thien Tran, et al