01 · AquaGrow
What it is
WFS describes whitish faecal strings in shrimp ponds, often alongside digestive problems and poor growth. Inspect shrimp as well as floating material: a white line on the water cannot identify a pathogen or determine which intervention is appropriate.
Signs to watch for
- White or pale faecal strings accumulate on the surface or near pond edges.
- Some shrimp show a whitish gut or faecal string at the anus.
- Reduced feeding, uneven growth, and sometimes continuing mortality accompany the signs.
Common causes
- WFS is multifactorial. Experiments have reproduced it with EHP plus a particular Vibrio isolate, and separate work with combinations of other Vibrio species. No single cause explains every pond.
- Similar signs can have other causes: Pale floating debris that is not confirmed to be shrimp faeces. Other gut or hepatopancreas disorders, including EHP without visible WFS.
How to confirm the cause
- Ask a qualified aquatic animal health professional and appropriate laboratory to examine fresh faecal material and affected shrimp. Histology helps distinguish digestive damage, microbes, and shed tissue.
- Select EHP PCR (a laboratory test for genetic material) and other pathogen tests from the clinical investigation. Vibrio isolation or a positive EHP result alone does not explain all WFS cases; interpret results with lesions and pond history.
What to do immediately
- 1
Photograph fresh strings and note where, when, and how often they appear.
- 2
Arrange professional examination and laboratory sampling of live affected shrimp.
- 3
Check oxygen and feeding response; correct measured water problems cautiously.
- 4
Restrict transfers and review deaths, growth, and feed use with the professional before deciding further action.
Prevention: your practical checklist
- Use traceable, appropriately screened seed and maintain pond separation.
- Match feed to observed consumption and protect stored feed from moisture.
- Manage faeces and settled waste without spreading sludge between ponds.
- Maintain oxygen and record water changes, blooms, and feed batches.
- Clean pond equipment and plan source-water and between-crop biosecurity.
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 white faeces always mean EHP?
No. Laboratory studies support an EHP role in some combinations, but other microbial combinations have also reproduced WFS. EHP testing is useful when indicated, not a substitute for investigating the syndrome.
Can a probiotic be guaranteed to stop WFS?
No. A tested experimental formulation and a commercial pond product are not equivalent. Ask the professional for evidence relevant to the identified problem; avoid changing several products simultaneously because the response becomes difficult to interpret.
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.
- Experimental reproduction of White Feces Syndrome in whiteleg shrimp, Penaeus vannamei ↗PLOS ONE; Aranguren Caro et al., 2021
- Rationally designed probiotics prevent shrimp white feces syndrome via the probiotics–gut microbiome–immunity axis ↗npj Biofilms and Microbiomes; Sha et al., 2024
- White Feces Syndrome of Shrimp Arises from Transformation, Sloughing and Aggregation of Hepatopancreatic Microvilli into Vermiform Bodies Superficially Resembling Gregarines ↗PLOS ONE; Sriurairatana et al., 2014
- Dense populations of the microsporidian Enterocytozoon hepatopenaei (EHP) in feces of Penaeus vannamei exhibiting white feces syndrome and pathways of their transmission to healthy shrimp ↗Journal of Invertebrate Pathology; Tang et al., 2016