A study on the prevalence and management of Running Mortality Syndrome (RMS) disease in Litopenaeus vannamei (Boone, 1931) farms of West Godavari District, Andhra Pradesh, India

Abstract

Running Mortality Syndrome (RMS) has emerged as a chronic production-limiting condition in intensive Litopenaeus vannamei aquaculture systems across Asia, including India. Unlike acute viral outbreaks, RMS is characterized by gradual mortality, growth retardation, empty gut syndrome, pale hepatopancreas, muscle degeneration, and persistent suboptimal survival, leading to substantial economic losses. The present study investigated the prevalence, environmental associations, pathological manifestations, production impact, and management strategies of RMS in commercial shrimp farms of West Godavari District, Andhra Pradesh, India. A total of 72 farms were surveyed across three culture seasons (pre-monsoon, monsoon, and post-monsoon) using cross-sectional and longitudinal sampling frameworks. Clinical screening, histopathology, microbiological assays, and environmental monitoring were conducted following standard aquatic animal health protocols. RMS prevalence was estimated at 28.4% (95% CI: 23.1-34.5%), with higher occurrence during post-monsoon months. Affected ponds showed significant associations with elevated sediment total organic carbon (TOC), ammonia concentrations >0.5 mg L⁻¹, dissolved oxygen fluctuation, and high stocking density (p < 0.05). RMS-positive ponds exhibited reduced average body weight (ABW) by 17-22%, increased feed conversion ratio (FCR) by 0.3-0.5 units, and survival reduction of 12-18% compared to unaffected ponds. Multivariate logistic regression identified sediment TOC, ammonia, and stocking density as significant predictors (AUC = 0.81). Histopathology revealed chronic degenerative changes including midgut epithelial sloughing and muscle fiber vacuolation. The study demonstrates that RMS is primarily ecosystem-structured rather than pathogen-dominant and underscores the importance of sediment management, nitrogen control, and aeration optimization in disease mitigation. An integrated ecological risk framework is proposed for sustainable management of RMS in Indian shrimp aquaculture.