Effect of dietary probiotic (Lactococcus lactis subsp. cremoris) and prebiotic (Mannanoligosaccharide) on growth performance and disease resistance against aeromonas hydrophila in gold fish (Carassius auratus, l.1758)

Bacterial diseases in aquarium fish are an important problem that causes serious economic losses. Aeromonas hydrophila is the causative agent of Motile Aeromonas Septicemia (MAS). In this study, a feeding experiment was conducted to examine the effects of dietary administration of probiotic (Lactococcus lactis subsp. cremoris, LAB), prebiotic (mannanoligosaccharide, MOS) and symbiotic (Lactococcus lactis subsp. cremoris and MOS) on growth performance and disease resistance of gold fish, Carassius auratus (mean initial body weight 4,32 g ± 0.68). Eight experimental diets were prepared to contain probiotic (108 cfu g−1 LAB), prebiotic (2 g kg-1 MOS), symbiotic (108 cfu g−1 LAB+ 2 g kg-1 MOS) and control (untreated). The experiment was conducted in 8 aquariums (70x30x40 cm) for 8 weeks. At the beginning of the experiment, 40 gold fish were stocked into each aquarium. After 8 weeks of feding, the fish were challenged intraperitoneally with Aeromonas hydrophila at LD50 dose (2,75.104 cfu ml-1). Mortality were recorded over 15 days and relative percentage of survival values calculated based on mortalities. As a result of this stuy, the addition of single or combined supplementation of prebiotic and probiotic to diets did not effect on the growth parameters (final weight, specific growth rate and weight gain). The fish fed with probiotic (Lactococcus lactis subsp. cremoris) supplemented diets did not improve protection against A.hydrophila. However, there were a singnificant decrease in fish fed with prebiotic (mannanoligosaccharide, MOS) and symbiotic (LAB+MOS) in mortality from A.hydrophila compared to control fish. RPS values were calculated as 50% in fish fed with prebiotic and symbiotic groups. These results suggest that prebiotic (MOS) or symbiotic application (Lactococcus lactis subsp. cremoris and MOS) can be used to increase resistance to Aeromonas hydrophila infection in gold fish.