Int.J.Curr.Microbiol.App.Sci (2018) 7(4): 2329-2340 2329 Original Research Article https://doi.org/10.20546/ijcmas.2018.704.267 Antibacterial Effects of Eisenia fetida, Earthworm Extract against Pathogenic Bacteria Isolated from Cyprinus carpio Nitish Bansal 1* , Rajender Kumar Gupta 1 and Vikas Nehra 2 1 Department of Zoology and Aquaculture, Chaudhary Charan Singh Haryana Agricultural University, Hisar (Haryana) - 125004, India 2 Department of Veterinary Pathology, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar (Haryana) - 125004, India *Corresponding author ABSTRACT Introduction Fishery is an important sector in India as it provides employment to millions of people and also contributes to the food security of the country. Massive fish mortalities have been reported from different countries due to bacterial, fungal, viral and protozoan infections/diseases that results in heavy economic losses. A variety of Bacterial infections pose significant threats to successful fish production throughout the world. Diseases as well as environmental pollution play an important role in aquaculture growth. Bacterial diseases outbreaks impose a significant constraint in fish and shellfish production (Bachere et al., 1995; Verschuere et al., 2000; Gomez et al., 2007). Bacterial International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 7 Number 04 (2018) Journal homepage: http://www.ijcmas.com In the present investigations, whole body extract of earthworm, Eisenia fetida was tested for antibacterial activity against fish bacterial pathogens. The bacteria were isolated from different tissues of infected common carp, Cyprinus carpio and identified by gram staining method. A total of eight pathogenic bacteria were isolated. Antimicrobial activity of the extract was studied under in vitro conditions by well diffusion assay. The extract of Eisenia fetida showed antibacterial activity against all the pathogenic bacteria and the maximum zone of inhibition was observed against A. hydrophila. Histological investigations had revealed that feeding the fish on a diet prepared by incorporating earthworm extract resulted in an increase in intestinal folds while injecting the fish with A. hydrophila resulted in degeneration and desquamatation of intestinal epithelium feeding on supplementary diet. When a healthy carp was injected with pathogenic bacterium and also fed on a diet prepared in earthworm extract, it resulted in a significant (P<0.05) increase in intestinal folds, intestinal microvilli, increase in concentration of melano-macrophage centre and also haemopoietic tissue in the kidneys. From these studies, it was concluded that the earthworm extract possesses very strong antibacterial properties which could be employed in treating bacterial infections in fishes, leading to the availability of antibiotic free fishes to the consumers. Keywords Bacteria, Common carp, Eisenia fetida, Antibacterial activity, Intestine, Kidney Accepted: 20 March 2018 Available Online: 10 April 2018 Article Info