White Feces Disease (WFD) in the culture of L Vannamei | Aquaculture Technology
Disease outbreak causing mass mortality in shrimp farms is common especially in a farm that has been operating for more than 2 years. Penaeus vannamei, as compared to mudcrab is more susceptible to disease. The disease might come from various pathogens such as bacteria, parasites, viruses and fungi. Unfavourable environments such as algae crash, rising total ammonia nitrogen (TAN), presence of protozoa, high organic load, high total Vibrio count in water, low transparency, high alkalinity and long exposure to low dissolved oxygen will cause stress in the culture organisms. The disease outbreak will occur when there’s subpar environmental conditions and the presence of pathogens, coupling with the lowering of the immune system of the culture organism due to stress, which then lead to mortalities. In this post we will touch on the White Feces Disease (WFD).
White feces disease (WFD) is among one of the most serious diseases in L.Vannamei. WFD causes significant economic losses to shrimp farmers, just like all the other diseases, mostly because of the high feeding conversion ratio (FCR), slow growth and variable sizes of shrimp at harvest.
The first WFD sign can be easily diagnosed when there is presence of white feces on the surface of the culture water. WFD is often related to the presence of Vibrio spp. in the culture environment, whether from water or food. Other signs and symptoms of WFD in shrimp are 1) dark discoloration of the gills, 2) hepatopancreas and gut become white and pale colour 3) infected shrimp show loose shell 4) slow growth.