01 · AquaGrow
What it is
Farmers use RMS for continuing low-level deaths rather than a single sudden crash. It is a description of a problem, not the name of one established pathogen or a stand-alone laboratory diagnosis.
Signs to watch for
- A few sick or dead shrimp are found repeatedly over several days.
- Feed response, activity or growth changes; some affected animals may show pale muscle patches.
- Estimated survival or biomass falls behind expectations; counting visible dead shrimp alone underestimates total loss.
Common causes
- The underlying cause is not settled for every situation described as RMS. Infectious, environmental and management-related problems need to be investigated rather than assumed from the label.
- Similar signs can have other causes: Repeated overnight low oxygen, poor bottom conditions or chronic water-quality stress. Confirmed infections or nutritional problems causing a similar persistent mortality pattern.
How to confirm the cause
- Arrange an aquatic-health assessment of live affected shrimp, mortality history, feeding, water trends and pond-bottom condition.
- Use laboratory tests selected from the findings, potentially including microscopy, histology (microscope examination of tissue) and pathogen-specific tests. A negative panel does not by itself diagnose RMS or prove that all infection is absent.
What to do immediately
- 1
Start a dated pond-level record: count observed deaths, describe behaviour and record feed response.
- 2
Check oxygen promptly and review recent rainfall, bloom changes, inputs and sludge disturbance.
- 3
Contact a qualified professional for a structured investigation and suitable laboratory samples.
- 4
Reassess population and crop economics using explicit uncertainty; make harvest or containment decisions with the professional, not from a fixed “RMS medicine” recipe.
Prevention: your practical checklist
- Keep daily feed, mortality and water records rather than waiting for a major crash.
- Maintain reliable overnight aeration and measure oxygen at vulnerable times.
- Match feed and stocking to actual pond capacity and manage organic waste.
- Use traceable seed and keep pond-specific gear to reduce cross-contamination.
- Plan timely professional follow-up when low-level losses begin, with records for comparison.
When to call an expert
- Call an aquatic animal health professional urgently if deaths rise, shrimp gather at the surface, or breathing becomes difficult. Check dissolved oxygen while arranging help.
- Arrange an assessment if these signs persist, feeding falls or growth stays behind the crop trend. Send water readings, recent input records and photographs; ask the laboratory how to collect samples.
Farmer questions
Only a few shrimp die each day. Can I wait?
Repeated losses can accumulate, and the visible count may miss deaths on the bottom. Record the pattern and seek assessment early rather than waiting for a large visible loss.
The PCR panel is negative. Is it definitely RMS?
No. It only reports the tested targets in the submitted samples. Sampling quality, timing, other agents and environmental causes still need review.
What should I record before asking for help?
Note the pond ID, culture day, recent deaths, feed intake, water test readings and recent changes. Ask the laboratory about suitable samples before adding a treatment. A photograph alone cannot confirm the cause.
Sources & further reading
AI-assisted educational content and translations, source-checked 17 October 2026. Not an individual diagnosis or prescription. Independent aquaculture-health and native-language specialist approvals have not been supplied. Sources do not endorse AquaGrow.
- Training manual on shrimp culture and disease management in inland saline areas — section 5.5, RMS ↗ICAR-CIBA, December 2022; historical technical reference
- Joint research and farmer outreach on unexplained running mortalities, August 2025 ↗ICAR-CIBA
- Better Management Practices — monitoring and farm biosecurity ↗MPEDA