Decoding EHP — why shrimp eat but won't grow & how to respond

1. What EHP is and how it spreads

EHP (Enterocytozoon hepatopenaei) is an intracellular microsporidian parasitizing the hepatopancreatic tubule epithelial cells of whiteleg shrimp. EHP spores are extremely resilient — surviving months in pond bottom mud and equipment — and spread through: water, fresh feeds (polychaetes, squid), infected post-larvae, and unsterilized inter-pond tools.

2. Why EHP-infected shrimp “eat but don't grow”

EHP hijacks energy and lipids in hepatopancreas cells — exactly what shrimp need for feed conversion and moulting. Consequences:

• FCR rises from 1.1 to 1.5 – 1.8 while feeding response stays strong.
• Growth drops 30 – 60% versus uninfected ponds.
• Uneven moulting, soft shells, scattered size distribution.
• Pale liver, thin gut, but no acute symptoms.

3. EHP prevention — starts at the hatchery

• PCR-test every PL batch for EHP — mandatory, no compromise.
• Sun-dry the pond bottom 7 – 10 days + apply high-dose CaO lime (kills spores).
• Disinfect inflow water with chlorine 30 ppm + 5-day evaporation.
• Avoid fresh feeds (squid, polychaetes) for shrimp older than 30 days.
• Disinfect inter-pond equipment with chlorine 1,000 ppm.

4. Already-infected ponds — a “coexistence” protocol

Once PCR-confirmed, the goal shifts to lowering disease pressure and compensating nutrition so shrimp still reach harvest size:

• FLASH 5 g/kg + CLEVER 5 g/kg feed — co-control EHP and Vibrio, from day 15.
• AQUAMOS 3 – 5 g/kg — inactive yeast + beta-glucan for cellular immunity.
• HERB GUARD 5 – 7 ml/kg in 5-day rotations — keep hepatopancreas functional.
• PRO GUT or PRO SUR — maintain gut mucosa for mineral absorption.
• Seed SOILMAX / LALSEA BIOREM every 4 – 5 days to reduce spore load.

5. When to consider early harvest

If after 30 days of protocol, FCR remains > 1.8 and size dispersion > 30%, consider early harvest to limit losses. Post-harvest, treat the pond thoroughly (sludge removal, sun-drying, CaO lime 1,000 kg/ha) before the next cycle. Contact Than Vuong technicians for the standard “EHP sterilization” procedure for both lined and earthen ponds.