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Research Article | 25 Jun 2026

Host-associated Enterococcus faecium isolated from Naleh fish (Barbonymus sp.) enhances growth performance, feed utilization, and water quality in common carp (Cyprinus carpio)

Cut Yulvizar1,2, Yulia Sari Ismail2, Cut Nanda Defira2, Puja Nabila Agustina2, Chendrastyan Meuraxa3, Dewi Yunita4, Zainal A Muchlisin3, and Suhartono Suhartono2 Show more
VETERINARY WORLD | Article No. 23 | pg no. 2585-2596 | Vol. 19, Issue 6 | DOI: 10.14202/vetworld.2026.2585-2596
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ABSTRACT

                      
Background and Aim: Common carp (Cyprinus carpio) is an economically important freshwater aquaculture species; however, its production is often constrained by poor feed efficiency (FE), disease susceptibility, and deteriorating water quality. Probiotics, particularly lactic acid bacteria (LAB), have been widely applied to improve fish performance and culture conditions. Host-associated probiotics candidate isolated from phylogenetically related fish species may provide superior colonization and biological benefits compared with non-native strains. Indigenous LAB isolated from Naleh fish (Barbonymus sp.), a native freshwater species in western Aceh, Indonesia, may serve as a host-associated probiotic candidate for common carp (C. carpio), as both species belong to the family Cyprinidae. This study evaluated the effects of LAB NJ19, an indigenous isolate obtained from the digestive tract of Naleh fish (Barbonymus sp.), on growth performance, feed utilization, survival, and water quality in common carp. 
Materials and Methods: A 40-day feeding trial was conducted using a completely randomized design with three treatments and four replicates: control diet without probiotics, diet supplemented with LAB NJ19 at 1 g/100 g feed, and diet supplemented with the commercial probiotic EM-4 (PT Songgolangit Persada, Jakarta, Indonesia) at 1 g/100 g feed. Juvenile C. carpio with an initial weight of 1.14 ± 0.07 g and length of 4.15 ± 0.10 cm were stocked at 10 fish per container. Molecular identification of LAB NJ19 was performed through 16S rRNA gene sequencing. Growth performance, feed conversion ratio (FCR), FE, survival rate (SR), and water quality parameters were evaluated. Data were analyzed using one-way analysis of variance followed by Duncan’s multiple-range test, with significance set at p < 0.05. 
Results: Sequence analysis demonstrated that LAB NJ19 shared 99.46% similarity with Enterococcus faecium and clustered within the E. faecium clade. Dietary supplementation with probiotics significantly improved growth performance and feed utilization compared with the control (p < 0.05). Fish fed LAB NJ19 exhibited the highest absolute weight gain (7.31 ± 0.29 g), specific growth rate (2.13 ± 0.03%/day), and FE (81.22 ± 3.26%), together with the lowest FCR (1.23 ± 0.04). The commercial probiotic EM-4 also enhanced growth and feed utilization, but was less effective than LAB NJ19 in improving growth-related parameters. SRs ranged from 67.50% to 77.50% and did not differ significantly among treatments (p > 0.05). Water quality remained within acceptable limits throughout the experiment. 
Conclusion: The indigenous host-associated probiotic candidate LAB NJ19, identified as E. faecium, significantly enhanced growth performance, feed utilization efficiency, and water quality in C. carpio. These findings highlight the potential of host-associated LAB as sustainable alternatives to commercial probiotics and support their use to improve productivity and environmental management in freshwater aquaculture systems. 
                      
Keywords: aquaculture, common carp, Enterococcus faecium, feed efficiency, growth performance, host-associated probiotic, lactic acid bacteria, water quality.