Encapsulation for delivering bioactives in aquaculture

The exploitation of wild fisheries has driven the seafood industry to develop more sustainable resources and high-intensity aquaculture. However, high-density aquaculture is prone to outbreaks of diseases. The use of chemicals and antimicrobial drugs in aquaculture is common practice, but such chemicals can have serious detrimental environmental impacts and antibiotics may result in bacterial resistance in many species. The development of non-antibiotic and green strategies, such as using probiotics and immunostimulants, aims for a more sustainable practice for health maintenance in aquaculture. Although the efficacy of such strategies has been demonstrated in cultivations settings, the effective delivery of bioactives remains a challenge. Conventional delivery methods are often ineffective in terms of dosage, stability and species specificity, and can possibly cause widespread environmental contamination. However, recently developed drug delivery systems may provide innovative ways to improve delivery with minimal waste and improved environmental protection. Indeed, such cutting-edge drug delivery systems have already provided measurable benefits in human medicine over the past two decades. New technologies, such as encapsulation and controlled release systems, can be used readily in scaled-up operations to improve the delivery of bioactives and ultimately increase production and profitability in aquaculture. This review critically analyses the use of encapsulation technology with a focus on microparticles for delivery of bioactive agents to farmed aquatic animals. This review discusses various potential encapsulation materials, their properties and a range of methods that can be applied and scaled-up for aquaculture. Finally, practical considerations for designing an efficient delivery system for aquaculture are discussed.