Effects of Different Levels of Dietary Surfactin Supplementation on Intestinal Morphology, and Intestinal Microflora of Growth Retarded Marbled Eel Juveniles (Anguilla marmaorata)

This 70 day trial was conducted to investigate the effects of surfactin on intestinal morphology and intestinal microflora of growth retarded marbled eels (Anguilla marmorata). A total of six hundred and forty marbled eels at elver stage were randomly allocated to 4 treatment groups on the basis of body weight. There were 4 replicate tanks in each treatment group with 40 fish per tank. Four diets were formulated with four levels of dietary surfactin: 0, 25, 50, and 100 mg/kg, respectively. Fish were fed twice daily to apparent satiation for 70 days. Retarded marbled eels fed diets with surfactin supplementation had enhanced mucosa folds in their intestines (P<0.05). It seems that the quantity of mucosa folds increased with the increasing surfactin levels in the diet. Dietary surfactin supplementation decreased the E. coli population significantly (P<0.05), and increased the Lactobacillus population significantly (P<0.05), but had no effect on total bacterial population in intestines of marbled eels (P>0.05). Results of the present study indicate that surfactin improves intestinal function in retarded elvers of marbled eels.