Carp polyculture has dominated freshwater aquaculture in South Asia for decades, providing economic returns and yield but often failing to address micronutrient deficiencies in rural diets. Recognising this gap, integrating SIS such as Mola into traditional carp farming systems represents a transformative approach1. These fish thrive alongside carp without additional feed inputs, creating nutrient-rich ponds that enhance the availability of essential micronutrients.

Empirical evidence from Bangladesh, India, and Nepal demonstrates the effectiveness of this integration. In Odisha and Assam, household ponds co-culturing carp and Mola increased access to vitamin A, calcium and iron, particularly benefiting women and children2. Importantly, these interventions are low-cost, requiring no additional feed inputs. By aligning aquaculture practices with nutritional objectives, this approach addresses malnutrition while maintaining the ecological balance of pond systems.
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1 Dubey SK, Rajts F, Gogoi K, Das RR, Padiyar A, Belton B, Mohan CV and Bhadury P. (2024). Mass scale seed production of indigenous small fish species: A promising solution to scale nutrition-sensitive aquaculture. In Sinha A, Roy A and Gogoi P, eds. Perspectives and Applications of Indigenous Small Fish in India. Singapore: Springer Nature Singapore Pte Ltd, pp: 109-134. https://link.springer.com/ chapter/10.1007/978-981-97-1586-2_5

2 Dubey SK, Padiyar PA, Shenoy N, Gaikawad AB, Ratha BC, Mohan CV, Belton B. (2024). Scaling Community- Based Aquaculture for Enhanced Nutrition and Women’s Empowerment: Lessons from Odisha, India. Frontiers in Sustainable Food Systems, 8:1412686. https://10.3389/fsufs.2024.1412686
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Despite these advantages, a major barrier persists: limited availability of SIS seeds. Unlike carp, tilapia and catfish, which are produced through well-established hatchery techniques, SIS seed production has historically relied on wild broodstock collection, a method that is labourintensive, ecologically disruptive, and unsustainable. Artificial breeding techniques, which revolutionised large fish production decades ago, had not been adapted for SIS, despite their superior nutritional profile. Interestingly, related small fish species are bred in the aquarium trade, indicating a largely untapped opportunity for food systems.

Addressing this challenge, the WorldFish-led project “Taking Nutrition- Sensitive Carp-SIS Polyculture Technology to Scale” (2021–2024), supported by the German Federal Ministry for Economic Cooperation and Development (BMZ) and GIZ, aimed to overcome the critical bottleneck of limited SIS seed availability.

The project focused on Assam and Odisha, two ecologically and culturally diverse Indian states where small-scale freshwater aquaculture predominates and SIS are integral to local nutrition, culture, and livelihoods. Interventions were tailored to regional contexts, ensuring that technical innovations aligned with community practices. By establishing hatchery-based mass seed production, the project reduced dependence on wild broodstock and promoted sustainable, high-quality SIS seed for aquaculture.

The project developed breeding and mass seed production protocols for six key SIS species3: (i) Mola (Amblypharyngodon mola): rich in iron, zinc, calcium, vitamin A, fatty acids and amino acids; (ii) Pool Barb (Puntius sophore); (iii) Swamp Barb (Puntius chola): rich in fat-soluble vitamins (A, D, E and K), essential minerals, fatty acids, and amino acids; (iv) Tengara Catfish (Mystus tengara): high in protein, calcium, iron, zinc, and omega-3 fatty acids; (v) Reba Carp (Cirrhinus reba): contains vitamins A and D, selenium, potassium, and omega-3 fatty acids; and (vi) Climbing Perch (Anabas testudineus): high protein content, essential micronutrients, omega-3 fatty acids, and essential vitamins.

Producing SIS at scale required careful attention to biological and technical details. Protocols included broodstock pond preparation, harvesting and conditioning breeders, sex identification, induced breeding set-up, hormone dose, spawning, egg incubation, and harvesting hatchlings. Hormone doses were species-specific (0.5–1 ml/ kg bodyweight for females; 0.25–0.05 ml/kg for males)
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3 WorldFish (2024). Tiny Treasures, Big Impact. The Vital Role of Small Indigenous Fish in Nutrition and Livelihoods. A Photographic Sojourn of the Project “Taking Nutrition-Sensitive Carp-SIS Polyculture Technology to Scale”. New Delhi, India: WorldFish. Photo Book: 2024-88. https://hdl.handle. net/20.500.12348/6498
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Specialised hatchery infrastructure—including double-hapa tanks, oxygen-rich water and energy-efficient water management systems— ensured optimal spawning conditions. Robust live transport and nurseryrearing protocols enabled large-scale production even in small-scale facilities. The protocols are simple, replicable, and compatible with existing carp hatcheries, allowing operators to diversify species, increase income, and improve access to nutrient-rich seeds for communities.

Over three years, the project successfully standardised protocols for six species and produced over 52.57 million SIS seeds, equivalent to approximately 20 782 kg of surviving fry. These seeds were distributed to farmers, women’s self-help groups, cooperatives, NGOs, and research institutions, promoting widespread adoption of SIS aquaculture.

The project integrated environmental manipulation with hormoneassisted breeding to maximise seed production. A key innovation was the development of multi-utility and mobile hatchery systems. Recognising that large, capital-intensive facilities were inaccessible to smallholders, modular hatcheries were designed to operate efficiently in floodprone and resource-limited regions4. Innovations included customised spawning and incubation tanks, cylindroconical incubators, aeration towers and plankton-based nursery and broodstock pond management. These innovations significantly improved hatching success, enabling small-scale hatcheries to produce high-quality SIS seed alongside carp.
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4 Rajts F, Dubey SK, Gogoi K, Das RR and Padiyar A. (2024). Small-scale alternative hatchery methods for indigenous small fish and minor carp seed production: A practical booklet. Penang, Malaysia: WorldFish. Booklet: 2024-22. https://hdl.handle.net/20.500.12348/5980
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In flood-prone and climate-vulnerable regions, mobile and small-scale hatcheries offered flexible, low-cost solutions. These systems required minimal installation and operational costs, were energy-efficient, and adaptable to local conditions. By integrating climate adaptation, water resource management, and sustainable energy use, these models provide resilient solutions for smallholder aquaculture.

Equally transformative was the economic model of SIS hatcheries developed to guide hatchery owners, cooperatives and policymakers5. Through detailed cost–benefit analyses, the project identified multiple entry points: integrating SIS seed production into existing carp hatcheries for an investment of around USD 5 500; establishing dedicated SIS hatcheries for USD 10 000; or setting up larger multi-species hatcheries with integrated research facilities for around USD 23 000. These models offered realistic and scalable pathways for small enterprises, cooperatives, and even public institutions to participate in the SIS value chain.

In partnership with state and national government agencies in India, the project implemented a comprehensive, multi-layered capacity-building strategy, engaging a diverse set of stakeholders, including government fisheries departments, private hatchery operators, farmers, NGOs and extension officers.

Training programs were designed to combine grassroots empowerment with high-level technical knowledge exchange, ensuring the long-term sustainability and adoption of SIS aquaculture practices. Knowledge exchange across India, Bangladesh and Cambodia enabled replication of SIS breeding protocols, facilitating a regional network of best practices.
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5 Chand BK, Dubey SK, Padiyar AP, Gaikwad AB, Das RR, Gogoi K and Rajts F. (2025). Economic analysis of the business model for mass seed production of nutrient-dense small indigenous fish species mola (Amblypharyngodon mola). Journal of the World Aquaculture Society, 56(4), e70038. https://doi.org/10.1111/ jwas.70038
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In Bangladesh, trained hatcheries achieved remarkable success, producing over two million Mola seeds in a single batch, an important milestone illustrating the feasibility of cross-border adoption of the project’s innovation. Initially supported by the CGIAR Initiative on the Asian Mega Delta, this SIS breeding package is now being further scaled through the CGIAR Scaling for Impact program, demonstrating the potential for regional expansion.

Overall, the project directly engaged 2 650 individuals, with women representing 35% of participants, which is a significant step toward inclusive, large-scale adoption of nutrition-sensitive aquaculture practices.

The success of hatchery-based SIS production has informed policy and programmatic decisions. In Odisha, the Department of Fisheries incorporated Mola hatcheries into State schemes under the World Banksupported project Odisha Integrated Irrigation Project for Climate Resilient Agriculture. Seven hatcheries were established with subsidy support, demonstrating a clear pathway from research innovation to institutional adoption. Earlier initiatives in 2018–19 had already integrated nutritionsensitive carp–Mola polyculture into community waterbodies via women’s self-help groups, providing a precedent for ongoing scale-up.

Looking ahead, a suite of strategic interventions is essential to sustain and expand the gains achieved in SIS aquaculture. At the national level, SIS should be formally recognised within fisheries and nutrition policies, integrated into flagship aquaculture programs, and incorporated into public nutrition initiatives, including school feeding schemes, maternal nutrition programs, and integrated child development services. Strengthening gender-inclusive policies is critical to promote women’s leadership in hatchery management, seed distribution, and decisionmaking across the value chain. Concurrently, raising awareness of the nutritional benefits of SIS and developing diversified, value-added products, such as dried, smoked, or fermented forms, can stimulate market demand and broaden their accessibility. Applied research remains central to scaling SIS aquaculture effectively. Efforts should focus on expanding hatchery protocols to additional SIS species, optimising carp–SIS polyculture under diverse ecological conditions and stocking densities, and investigating natural breeding dynamics in rice fields and semi-natural systems. Integrating SIS into wetland, floodplain, and open-water fisheries can enhance biodiversity while supporting smallholder livelihoods. The deployment of mobile and climate-resilient hatchery models will further strengthen system adaptability in the face of environmental variability.

Regional centres of excellence can serve as hubs for training, innovation, and cross-learning, ensuring that advances in SIS aquaculture are effectively disseminated and sustained. Collectively, these strategies can position SIS aquaculture as a scalable, nutrition-sensitive, and ecologically sustainable approach—simultaneously enhancing rural livelihoods, improving micronutrient intake, and conserving freshwater biodiversity across South Asia.