Early Signs of AHPND (EMS) — Look at the Hepatopancreas

AHPND (acute hepatopancreatic necrosis disease, also called early mortality syndrome) is one of the most destructive diseases in whiteleg shrimp farming. It is caused by toxin-producing Vibrio strains, typically strikes 20–30 days after stocking, and once it starts it can take out an entire pond within days. There is no cure, so early detection and prevention are everything. ■ The first signal — reduced feed response Check the feed tray: feed that normally disappears within the usual window starts being left behind. This arrives before anything shows in your water numbers, and only farms that check trays daily will catch it. If intake drops 20–30% for no obvious reason, sample shrimp and inspect them the same day. ■ Inspect the hepatopancreas directly AHPND targets the hepatopancreas — the dark brown organ on the dorsal side of the head. Net a few animals, remove the shell, and compare by eye. Healthy — deep brown or dark yellow-brown, full in size, with clearly defined edges. Suspect — noticeably paler (light yellow, close to white), shrunken, and soft when pressed. In advanced cases black spots or streaks may appear. ■ Accompanying signs The shell softens and the body becomes translucent. The midgut is empty, so the dark line running along the back is absent — direct evidence the shrimp are not feeding. Growth visibly lags and size becomes uneven. Dead animals are found mostly on the pond bottom. ■ Reducing the conditions is the only real defence First, source post-larvae from screened suppliers. A large share of AHPND enters at the seed stage. Ask for and check PCR results before stocking. Second, bottom management is the core. Bottoms loaded with organic matter are ideal for Vibrio. Dry and clean the bottom thoroughly between cycles. During culture, avoiding overfeeding is the most effective bottom management there is. Third, do not push stocking density. Higher density raises stress and organic load together. Fourth, apply beneficial microbes consistently to leave Vibrio less room to establish. ■ If you suspect it, decide on isolation immediately Once confirmed in one pond, you must block transmission through water and equipment. Keep tools pond-specific and check your drainage routes. A day's delay in this decision costs you the neighbouring ponds. ■ Daily records are what make early detection possible The first sign of AHPND is a drop in feed intake. Recording daily feed and leftovers turns "less than usual" from a hunch into a number. Shrimp365 keeps feeding and mortality records together so anomalies surface fast. ※ This is field-observation guidance and does not replace diagnosis. If you suspect AHPND, get PCR testing from an aquatic animal health laboratory.