Off-season induced breeding of common carp (Cyprinus carpio Linnaeus, 1758) at the Fishery Research Station, Trishuli, Nepal

Abstract

Common carp (Cyprinus carpio) is a major aquaculture species in Nepal, but its breeding is mostly confined to spring, leaving mid-hill farmers dependent on seed from the Terai. To address this, the Fishery Research Station, Trishuli, tested a simple off-season induced breeding method from 2076 to 2082 BS (2019–2025). Broodstock were conditioned in earthen ponds with natural and protein-rich feeds, segregated during winter, and injected with Ovaprim before release into breeding ponds fitted with net substrates. Eggs adhered to the nets, hatched within 2–3 days, and fry were reared in the same ponds. Across six years, more than 125,000 advanced fries were produced annually under mid-hill water temperatures of 21–27°C, dissolved oxygen of 5–7.5 mg/L, and pH 6.7–8.2. The method required no hatchery infrastructure and was flexible in broodstock numbers and sex ratios. Results confirmed that good broodstock conditioning and stress-free handling were more important than precise environmental control. The technique enables farmers to produce quality seed locally, reducing dependence on Terai hatcheries and minimizing fry mortality from transport stress. Adoption of this low-cost, low-tech method can promote decentralized seed production, improve seed security, and enhance the livelihoods of smallholder fish farmers in Nepal’s mid-hills.