Evaluation of dissimilar intestinal bacteria incorporated feeds on growth of ornamental fish Swordtail Xiphophorus helleri

Four dissimilar bacterial colonies were isolated from the intestine of ornamental fish Swordtail Xiphophorus helleri through serial dilution. The isolated colonies were identified as Enterobacter sp., Bacillus sp., Streptococcus sp. and Pseudomonas sp. using biochemical tests. Enzyme productivity and antibacterial activity of intestinal bacteria of Swordtail were carried out against pathogens such as Enterococcus faecalis, Shigella flexneri, Streptococcus pyogenes and Klebshilla pneumoniae along with commercial antibiotic Tetracycline. Based on biochemical tests, enzyme productivity and antibacterial activity mass multiplication of Enterobacter sp., Bacillus sp. and Streptococcus sp. were done in nutrient broth. Four different feeds such as feed I (Control) (without bacteria), Feed II (1ml Bacillus sp.), Feed III (1 ml of each of Bacillus sp. and Streptococcus sp.) and Feed IV (1 ml each of Bacillus sp., Streptococcus sp. and Enterobacter sp.) were prepared. A total of 60 fishes were used for the study. Feed utilization parameters of the Swordtail were estimated after 21 days. Based on the antibacterial test, the Bacillus sp. and Enterobacter sp. have higher inhibition. Most of the feed utilization parameters were higher in feed IV. From the results, it was concluded that the combination of three dissimilar bacteria in the feed enhanced the growth of the Swordtail. Significance and Impact of the Study: In the aquaculture sector, ornamental fish culture provides excellent opportunities as non‐food fishery activity of employment and income generation. Ornamental fishes are susceptible to various pathogens and bacteria is the one cause of severe loss. The bacterial flora within the intestinal tract of fish positively induces the growth of fishes. Most of the studies are related to the isolation of bacteria from the intestine of fishes but the incorporation of the single bacterium in the feed. But the present work shows that the incorporation of dissimilar bacteria in the feed enhanced the growth of ornamental fish Swordtail and it will benefit the aquarium keepers.