Effect of Biofloc on the Survival of Whiteleg Shrimp, Penaeus vannamei Boone 1931, When Challenged with a Pathogenic Strain of Vibrio parahaemolyticus, the Causative Agent of Acute Hepatopancreatic Necrosis Disease (AHPND)

To understand better the effect of different water conditions on the survival of whiteleg shrimp, Penaeus vannamei, when challenged with a pathogenic strain of Vibrio parahaemolyticus (VP AHPND ), a series of challenge trials with biofloc were conducted.Challenges investigated the effect of holding individual shrimp for short periods (5-10 days) in either biofloc or in clear water prior to exposure to VP AHPND in either biofloc or in filtered biofloc.Shrimp reared and challenged in unfiltered biofloc had the lowest mortality rates (0 and 6.7 %; P < 0.05), followed by those held in clear water for 10 days and challenged in clear water (33.3 and 20 %; P < 0.05).Shrimp reared in unfiltered biofloc and but challenged in clear water had the highest rates of mortality (80 and 60 %).A second validation trial, included the use of filtered biofloc.Shrimp reared and challenged in unfiltered biofloc had the lowest rate of mortality (13.3 %), followed by those reared in biofloc but challenged in 2 µm-filtered biofloc (20 %).The highest mortality was in shrimp reared in biofloc but challenged in clear water (73.3 %; P < 0.01).The results demonstrate that biofloc can protect whiteleg shrimp from VP AHPND and that the management of biofloc in aquaculture ponds can assist in controlling bacterial infections.