Five-year Production and Economic Performance of Composite Carp Polyculture under Smallholder Management in Manipur, Northeast India: Implications for Aquaculture Extension

Smallholder aquaculture in Northeast India remains substantially below national productivity levels despite abundant freshwater resources, presenting a key opportunity for sustainable intensification aligned with SDGs 1, 2, and 14. This study documents the transition from subsistence monoculture to commercial aquaculture using a composite polyculture system (Indian major carps and grass carp) in Churachandpur district, Manipur. This study documents production metrics, economic returns, and management practices of a composite carp polyculture system (Indian major carps and grass carp) managed by 23 smallholder farmers in Churachandpur district, Manipur, across five consecutive production cycles (2018–2023). Performance was assessed using descriptive statistics, benefit-cost ratio (BCR), ROI, and independent samples t-tests (α = 0.05) against published monoculture baselines (n = 12 reference systems). The polyculture system achieved a mean production of 3,522 kg per cycle, with an average survival rate of 96.5% and a feed conversion ratio of 1.42. Economically, the system generated mean annual net returns of ₹458,160 per hectare with a benefit-cost ratio of 2.82. When compared against published monoculture reference data from South Asian systems, the polyculture demonstrated an estimated 119% higher productivity and approximately 387% greater net return per hectare per cycle (t(15) = 3.62, p = 0.003); these figures reflect comparisons against external literature baselines, not concurrent experimental controls. The significant progressive improvement in economic efficiency across the five years highlights strong learning-by-doing effects. These findings suggest that, with adequate extension support, composite carp polyculture offers considerable potential for sustainable intensification, contributing meaningfully to household livelihood security and rural aquaculture development in the region.