Characteristics of Lactic Acid Bacteria (LAB) isolated from rotifers, Brachionus plicatilis, resembled those of Lactobacillus plantarum or Carnobacterium sp. It was investigated whether the artificial maintenance of a high concentration of LAB in rotifers might increase their dietary value for turbot larvae, particularly when the fish were infected with pathogenic Vibrio sp. One LAB strain was cultivated, then introduced daily into the enrichment medium of rotifers. In this way, LAB were retrieved in large amounts in turbot, and a significant limitation of larval mortality rate was observed when turbot were challenged with pathogenic vibrio at day 9. The inoculum concentration of LAB had a decisive effect on survival rate, and the optimum was between 10(7) and 2 x 10(7) Colony Forming Units (CFU) daily added per ml of the enrichment medium (53% survival rate after 72 h of challenge, versus 8% for the infected control group without LAB).