Effective management of Mud crab Reovirus (MCRV) infection in mud crab, Scylla serrata (Forskal, 1775) culture, using an individual compartmentalized system.

Mud crab (Scylla serrata) aquaculture is a critical contributor to coastal economies and export markets in India. However, the sector faces significant challenges from Mud Crab Reovirus (MCRV), a highly pathogenic virus reported to cause mass mortalities and severe economic losses. This study assessed the performance of different rearing systems-open pen, cage-in-pen, and external cage systems-focusing on their efficacy in managing MCRV transmission, mortality, and production outcomes. The open pen system exhibited the highest mortality rate (73 ± 4.57 %) and MCRV infection rate (89.04 ± 3.04 %), primarily due to direct contact and cannibalistic behavior among crabs, which facilitated viral transmission. In contrast, the cage-in-pen and external cage systems significantly reduced mortality (18 ± 2.21 % and 19.1 ± 2.88 %, respectively) and MCRV prevalence (64.13 ± 4.35 % and 65.21 ± 3.78 %, respectively) by physically isolating individuals. These systems achieved higher production yields (11.2 ± 1.5 kg and 10.8 ± 1.8 kg) compared to the open pen system (3.5 ± 0.2 kg). Histopathological and transmission electron microscopy (TEM) analyses confirmed MCRV infection, with cytoplasmic basophilic and eosinophilic inclusions observed in the hepatopancreas, gills, and muscle tissues of infected crabs. TEM revealed icosahedral viral particles (∼70 nm) concentrated in the cytoplasm of connective tissue cells, validating previous findings on MCRV replication. This study highlights the critical role of individual compartmentalized systems, such as cage culture, in mitigating MCRV transmission and improving mud crab survival and productivity. While cage culture offers an immediate solution, long-term strategies like enhanced disease surveillance, selective breeding programs, and biosecurity measures are essential for sustainable mud crab aquaculture. These findings provide actionable insights for farmers and policymakers to strengthen the resilience of mud crab farming against MCRV outbreaks.