01 · AquaGrow
What it is
A sudden fall in feeding followed by increasing deaths needs urgent investigation. White spots are neither necessary nor sufficient to diagnose WSSV; apparently normal shrimp may also carry the virus.
Signs to watch for
- Feed trays suddenly retain more feed; shrimp become weak or gather at pond edges.
- Some animals turn pink or reddish; deaths may rise quickly.
- White marks may appear within the shell, but vannamei can be affected without obvious spots.
Common causes
- White spot disease is caused by white spot syndrome virus. It affects susceptible crustaceans, including vannamei. It is different from the white-spot parasite of freshwater fish.
- Similar signs can have other causes: Mineral deposits and some bacterial shell conditions can also create pale shell marks. Low oxygen, toxic-water events and other infections can produce weakness and sudden deaths.
How to confirm the cause
- Ask the laboratory for validated WSSV PCR (a laboratory test for genetic material) testing and appropriate representative samples; tissue examination may support the investigation.
- Interpret the result with signs, sampling quality and pond history. A negative batch sample does not guarantee future freedom from infection.
What to do immediately
- 1
Contact an aquatic animal health professional promptly; check oxygen and aeration immediately.
- 2
Record when feeding changed, the daily mortality and any recent water or animal movement.
- 3
Arrange sampling before applying unplanned treatments; coordinate containment with neighbouring farms and fisheries authorities where required.
- 4
Keep affected stock, equipment and water separate. Agree on safe disposal and any harvest or discharge with your professional.
Prevention: your practical checklist
- Choose traceable seed with an appropriate WSSV screening record; ask what any SPF (specific pathogen free for a stated list of pathogens) certificate actually covers.
- Prepare ponds between crops and manage intake water through a professionally designed biosecurity system.
- Maintain crab barriers and bird-risk controls, and avoid abrupt water-quality changes.
- Assign nets, trays and boots to each pond; clean and disinfect equipment under the farm’s biosecurity plan.
- Keep seed-batch, feeding, water-quality and mortality records so a change is noticed early.
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
No white spots: can it still be WSSV?
Yes. The name is misleading if used as a field test. Laboratory investigation is needed, especially when feeding drops and deaths increase.
Should I drain the pond immediately?
No uncontrolled discharge. It can spread infection. A professional must help decide containment, harvest, effluent treatment and the next-crop sanitation plan.
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.
- White spot disease — Technical Advisory Series No. 2 ↗ICAR–Central Institute of Brackishwater Aquaculture — Technical Advisory
- White spot disease — field signs and differential diagnosis ↗NACA / Australian Government — historical Asia–Pacific identification field guide; not current surveillance
- Better Management Practices for shrimp farms ↗Marine Products Export Development Authority (MPEDA)