Integrated Multi-Trophic Aquaculture (IMTA) is an ecologically-engineered system designed to enhance the sustainability and resilience of marine farming by integrating species from different trophic levels (fed and extractive) in close proximity. This creates a balanced, circular system where the waste generated by one species becomes a valuable input (fertilizer, feed, or energy) for another, moving aquaculture away from the linear, monoculture model. IMTA operationalizes an ecosystem-based management approach that carefully considers site specifications, operational limitations, food safety guidelines, and regulations. The system’s goals are holistic, which include: environmental sustainability achieved through biomitigation, the recycling of nutrients and wastes, which directly reduces eutrophication; economic stability is ensured by product diversification (cultivating multiple commercial crops) and risk reduction (less dependence on a single species) and social acceptability is supported by better management practices and a reduced ecological footprint. IMTA involves the intensive cultivation of species connected by nutrient and energy transfer through water, with the balance maintained by selecting appropriate species in the right proportions. Fed species (the input source) are high-value finfishes, such as cobia (Rachycentron canadum), Asian seabass (Lates calcarifer), pompano (Trachinotus mookalee, T. blochii), and orange spotted grouper (Epinephelous coioides), which serve as the major cultured components. Their metabolic waste and uneaten feed provide the primary nutrients for the extractive species (the biofilters/crops). These extractive species, which are more than just biofilters offer, commercial value, absorb and convert wastes into harvestable biomass. They include: organic extractive (suspension/deposit feeders) species, such as non-fed bivalves like mussels (Perna viridis, P. indica) and edible oyster (Crassostrea madrasensis), which filter the particulate matter and inorganic extractive species, primarily seaweeds, absorb dissolved nutrients. Red and brown seaweeds like Gracilaria edulis, Gelidiella acerosa and Kappaphycus alvarezii are widely used in IMTA. A successful IMTA results in better overall production and improved ecosystem health, even if the individual production of some species is slightly lower than in short-term, unsustainable monoculture practices. The scope for IMTA in India is exceptionally high due to the climatic advantage (tropical climate conducive to year-round farming), species diversity (established technologies for key finfishes and existing farming of extractive species), and increasing market demand for a variety of farmed species.
Key Words: Integrated Multi-Trophic Aquaculture (IMTA), Sustainability (or Sustainable mariculture), Trophic levels, Biomitigation, Product diversification, Extractive species, Monoculture