White Feces in Shrimp
By Dr. Wiphada Mitbumrung, Ph.D. Applied Marine Biosciences — Wed Jul 01 2026
In healthy shrimp, feces are normally brown to dark brown because they contain digested feed, bile pigments, intestinal content, and normal gut microorganisms. The fecal string is usually compact and sinks or breaks down naturally in the pond. White feces occur when digestion and absorption are disturbed. Instead of normal digested feed material, the feces contain more mucus, sloughed intestinal cells, undigested feed particles, bacteria, and sometimes damaged hepatopancreatic tissue. This makes the feces appear pale, whitish, loose, and floating on the water surface.
The main cause of white feces is often related to feed. Poor-quality feed, rancid oil, low-digestibility ingredients, excess feeding, or sudden feed changes can irritate the gut and reduce digestion efficiency. When feed is not properly digested, more undigested material remains inside the gut and pond environment. This reduces feed efficiency, increases organic loading, and creates favorable conditions for bacterial growth.
When feed is not fully digested by shrimp, bacteria become the main organisms that break down the remaining nutrients. Undigested feed is a rich food source for opportunistic bacteria, especially Vibrio spp. Under normal conditions, Vibrio may be present at low levels in the pond and shrimp gut. However, when excess undigested feed accumulates, Vibrio can multiply rapidly and become too concentrated. At this stage, Vibrio becomes a secondary cause of white feces by disturbing the gut microbiota, irritating the intestinal lining, increasing mucus production, and worsening digestive dysfunction.
Another secondary cause is Enterocytozoon hepatopenaei, or EHP. EHP affects the hepatopancreas, which is the main organ for digestion and nutrient absorption in shrimp. EHP usually does not cause sudden mortality by itself, but it reduces digestive efficiency, slows growth, and makes shrimp weaker. When EHP infection occurs together with poor feed digestion and high Vibrio pressure, white feces can become more severe and difficult to control.
White feces itself does not always directly cause mortality. However, it can lead to serious production losses if not managed early. Affected shrimp may reduce feed intake, show poor growth, become weak, and become more sensitive to environmental stress. Mortality can occur when white feces is associated with severe Vibrio infection, poor water quality, hepatopancreas damage, or secondary disease outbreaks. More importantly, if the Vibrio growing inside the shrimp gut carries the PirAB toxin plasmid, it can cause Acute Hepatopancreatic Necrosis Disease, or AHPND. In this case, white feces may be followed by rapid hepatopancreas damage and mass mortality.
Therefore, white feces should be treated as an early warning sign. Management should focus on improving feed quality, controlling feeding rate, reducing organic load, maintaining stable water quality, checking Vibrio levels, and screening for EHP and AHPND-causing Vibrio when necessary. Early response is important to prevent growth loss, health deterioration, and possible mortality.