The intestinal microflora of farmed Dover sole (Solea solea) at different stages of fish development

The bacterial flora in the intestines of farmed Dover sole ( Solea solea L.) was investigated at different stages of fish development in relation to different diets fed under farming conditions. The flora of water and diets were also analyzed. The dominant generic group isolated from all water samples examined was Pseudomonas Gp IV/ Alcaligenes. The same generic group was dominant in homogenized pelagic larvae indicating a relationship between the microflora of those young fish and that of tank water. In older fish a steady increase in the percentage incidence of Vibrio / anaerogenic Aeromonas was observed in the intestines as fish grew and diets changed. The Vibrio /anaerogenic Aeromonas group was dominant in Lumbricillus rivalis used as an intermediate diet and the increased incidence of this group in fish intestines occurred after fish were fed this diet. The composite pellet used for ongrowing carried a high percentage of Gram positive micro-organisms and there was no relationship between the pellet microflora and that found in the fish intestines.