Carp and tilapia contribute to more than 60% of aquaculture production worldwide. High demand of these species has led to the shift from extensive to intensive aquaculture practices. However, intensification of aquaculture systems is linked to risks of disease occurrence, which causes massive mortalities. Antibiotics have been used as growth promoters and to prevent disease in fish farming. However, these components pose a threat to public health and have a negative effect on the environment. The use of prebiotics is a strategy being studied to prevent these issues. The focus of the present study was to determine the impacts of prebiotic supplemented diets on growth and the microbial community composition of the intestinal tract of Nile tilapia Oreochromis niloticus and goldfish Carassius auratus, used as model cichlid and cyprinid species respectively.
Fingerlings of goldfish and Nile tilapia (1.4 g average individual weight) were cultured in tanks within a common recirculating system. Experimental diets consisted of fish feed supplemented with commercially available prebiotics (2%). Fructo- (diet One, FOS), isomalto- (diet Two, IMO), xylo- (diet Three, XOS), and galactooligosaccharides (diet Four, GOS). Two control diets were added. After completing the feeding trials, fish were euthanized for growth measurements and dissected for intestinal tissue sampling. Intestinal bacterial communities were determined using next generation sequencing.
Goldfish samples showed a higher microbiome diversity than that of Nile tilapia (Figure 1) and appeared to have a higher acceptance of the supplemented diets, which was exhibited in their feeding behavior and their final weight and length (P < 0.05). Results in this study suggest that the use of commercial prebiotics in intensive aquaculture systems may enhance fish growth and shape their intestinal microbiome. Different prebiotic concentrations, prebiotics combinations, and changes in the duration of feeding trials might yield different results.