01 · AquaGrow
What it is
IHHNV can be associated with uneven growth and deformities in vannamei. Not every infected population shows the same outcome, and not every small or bent shrimp has IHHNV.
Signs to watch for
- A widening spread of harvest sizes or falling average weight gain.
- Bent rostrum, abnormal body segments or tail deformity in some shrimp.
- Reduced feeding efficiency; infection may also occur without visible changes.
Common causes
- Infectious hypodermal and haematopoietic necrosis virus infects susceptible shrimp. Its effects differ between species, viral variants and stocks; severe mortality described in blue shrimp should not be automatically applied to vannamei.
- Similar signs can have other causes: EHP, poor seed quality, nutrition or unequal access to feed. Handling injury, environmental stress and other causes of deformity.
How to confirm the cause
- Use a validated IHHNV PCR (a laboratory test for genetic material) assay selected by the laboratory, with tissue examination if indicated. Some assays can detect noninfectious virus-related sequences in shrimp DNA (endogenous viral elements, EVEs); ask how the assay distinguishes these and confirms unexpected results.
- Review sampling, seed-batch history, weight distribution and other growth-related tests. Do not interpret a screening result in isolation.
What to do immediately
- 1
Arrange a professional assessment and appropriate laboratory tests.
- 2
Record average weight, size range, feed conversion assumptions and visible deformities.
- 3
Review feeding access and water quality while investigating infection; plan the crop using measured growth.
- 4
Keep affected stock, equipment and water separate. Agree on safe disposal and any harvest or discharge with your professional.
Prevention: your practical checklist
- Buy traceable PL with relevant pathogen-screening records and a documented hatchery health programme.
- Keep seed lots separate and check batch identity before stocking.
- Avoid transferring slow-growing shrimp into healthy ponds to improve their growth.
- 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
Does a bent rostrum prove IHHNV?
No. It is a reason to investigate, not a definitive test. Compare the population and use appropriate laboratory methods.
Can apparently healthy shrimp carry infection?
Yes. Appearance cannot replace the hatchery’s screening and biosecurity programme, and a single negative test is not an absolute guarantee.
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.
- Infection with IHHNV — diagnostic and disease information ↗World Organisation for Animal Health — Aquatic Manual (2023; assay limitations in section 4.4)
- IHHN — field observations and host differences ↗NACA / Australian Government — historical Asia–Pacific identification field guide; not current surveillance
- Cultured Aquatic Species Information: Penaeus vannamei — diseases and management ↗Food and Agriculture Organization of the United Nations (FAO); historical species profile