From waste to wellness: Citrus by-products as nutritional and immunological enhancers in aquaculture

What if the secret to healthier fish—and a more sustainable aquaculture—lies in the citrus peels you throw away? New research shows these overlooked by-products could boost fish growth and immunity.

The global appetite for seafood is growing, but aquaculture faces a triple threat: soaring feed costs, disease outbreaks, and environmental scrutiny. Enter citrus by-products—the peels, seeds, and pulp discarded by the juice industry. These humble leftovers are packed with bioactive compounds like flavonoids and polyphenols, offering a renewable resource for functional fish feed.

Green extraction technologies, especially ultrasound-assisted extraction, are unlocking this potential. They recover these valuable compounds with over 30% higher phenolic yields while slashing solvent use—a win for both efficiency and the planet.

When added to aquafeeds, citrus bioactives deliver real results. Lemon peel extracts boosted Nile tilapia survival past 80%, while bitter orange essential oil sped up growth and fine-tuned immune gene expression in common carp. The evidence is promising, yet mysteries remain: bioavailability, metabolic pathways, and species-specific responses are still poorly understood.

This review charts the path forward, synthesizing advances in green extraction and functional feed applications. It highlights critical research gaps—guiding the next wave of sustainable aquaculture innovation. From waste to wellness, citrus may just be the unexpected hero of the fish farm.

Key Points

• Ultrasound extraction boosts phenolic yields by >30% with less solvent.
• Citrus bioactives improve fish growth, immunity, and disease resistance.
• Lemon peel extract raised Nile tilapia survival to over 80%.