Copyright @ 2019, Indonesian Aquaculture Journal, p-ISSN 0215-0883; e-ISSN 2502-6577 69 Indonesian Aquaculture Journal, 14 (2), 2019, 69-74 # Correspondence: Department of Aquaculture, Faculty of Fisheries and Marine Science, Borneo University of Tarakan Jl. Amal Lama No. 1, Tarakan, Kalimantan Utara, Indonesia. Tel. + 62 811 530 7023 E-mail: diana.maulianawati@ gmail.com Available online di: http://ejournal-balitbang.kkp.go.id/index.php/iaj IN VITRO ANTIBACTERIAL EFFICACY OF LEAVES EXTRACT OF Centela asiatica AGAINST Vibrio harveyi AND Aeromonas hydrophila Rukisah, Diana Maulianawati # , and Jimmy Cahyadi Department of Aquaculture, Faculty of Fisheries and Marine Science, Borneo University of Tarakan Jl. Amal Lama No. 1, Tarakan, Kalimantan Utara (Received 20 September 2018; Final revised 18 January 2019; Accepted 23 January 2019) ABSTRACT Disease infection is one of the limiting factors that affect productivity in aquaculture and has caused economic losses. Luminescent vibrios and motile aeromonas septicemia (MAS) are diseases caused by Vibrio harveyi and Aeromonas hydrophila bacteria, respectively. Certain plants have antimicrobial compounds and can potentially be used to treat the diseases, such as Centella asiatica. In the present study, the crude leaves extracts of C. asiatica were examined for its antibacterial potential using methanol solvents against V. har veyi and A. hydrophila bacteria. Different concentrations of 50 mg/mL and 100 mg/mL were checked for its antibacterial activity. The crude extract was also tested for phytochemistry content and LC 50 using Brine Shrimp Lethal Assay. The crude extracts of C. asiatica showed a remarkable antibacterial activity with inhibition zone of 10.57 mm against A. hydrophila and 21.14 mm against V. harveyi . The phytochemistry test result showed that C. asiatica leaves contain alkaloid, phenol, and tannin compounds. The acute lethal concentration (LC 50 ) of C. asiatica after 24 hours exposure to the extract mixture was 254 mg/L. The results confirmed the potential use of C. asiatica extracts as a source of antibacterial compounds. KEYWORDS: antibacterial; Centella asiatica; Vibrio harveyi; Aeromonas hydrophila INTRODUCTION Aquaculture is the fastest-growing food-pro- ducing sector in the world with annual growth reaching 9% . This growth is driven by the increased of seafood demand along with global population growth (Allan & Burnell, 2013). Aquaculture activities are not only re- quired to be able to provide food source but also to sustain aquaculture production and product trade. The growth of aquatic biota was influenced by infection of diseases. Disease infection is one of limiting fac- tors that affect productivity in aquaculture and has caused economic losses due to various diseases caused by bacteria, fungi, parasites, and viruses (Flegel et al ., 2008). Here, we focus on disease caused by luminescent vibrios (i.e., Vibrio harveyi ) and motile aeromonas septicemia (MAS) diseases caused by Aeromonas hydrophila. Vibrio harveyi is a bacterium that causes shrimp mass mortality. These bacteria attack shrimp larvae in hatcheries and shrimp cultivated in on growing ponds and known as luminescent shrimp dis- ease. The shrimp infected by this bacteria will glow in the dark and usually attack the larvae at zoea, mysis and post larvae stages. V. harveyi are gram-negative, usually motile rods, facultative anaerobes and types of bacteria that live in the sea and have high salinity resistance (Thompson et al ., 2004). While A. hydrophila attacked all types of freshwater fish in the tropics and were often isolated from diseased catfish. This disease usually occurs when the fish con- dition decreases due to stress and poor water quality (Sarono et al ., 1993). There are many approaches and mitigation efforts to reduce the negative impacts caused by pathogenic agents, including the use of high quality seed, best culture management, and application of biotech- nology. In addition, many farmers, especially in developed countries, have improved their capacity to respond quickly and effectively to emergent disease situations. In most developing countries, the use of antibiotics is common to control fish disease distribution. However, antibiotics to treat bacterial diseases has been prohibited because uncontrolled antibiotics use may lead to resistant bacteria. This is