Siamese Fighting Fish (Betta splendens Regan) Gut Microbiota Associated with Age and Gender

Abstract

The Siamese fighting fish (Betta splendens Regan) is a popular ornamental fish in Thailand. Growing research suggests that fish health is influenced by gut microbiota. Here, we investigated, for the first time, the differences in the gut microbiota profiles of healthy Siamese fighting fish during the young (8-week-old) and adult male and female (16-week-old and 24-week-old) life stages using 16S rRNA gene sequence analysis. The fish were raised in controlled water quality conditions and fed on Moina macrocopa. Profiling of gut microbial communities revealed significant differences in the overall bacterial profile between young and adult Siamese fighting fish. Bacterial diversity decreased in the 24-week-old adult fish. Proteobacteria was the most predominant bacterial phylum in the gut of both young and adult carnivorous betta fish, in which the abundance of its members varied with age. Plesiomonas was enriched in male fish aged 24 weeks, whereas Pseudomonas dominated the gut of 8-week-old fish. Moreover, differences in predicted functions of these Proteobacteria between the young and adult fish could be a key target for improving fish growth. These findings expand our understanding of the role of gut microbiota and its association with host factors.