ABSTRACT The purpose of this study was to identify and evaluate prevalence of Aeromonas hydrophila bacteria that attack African catfish farmed fish in Aceh Besar district with the microbiological test. This study was conducted on March 2016. Samples were collected from the District recorded have African catfish fish in Aceh Besar district, namely the District Baitussalam. Observations conducted in the laboratory bacteria Bacteria Quarantine Fish Quality Control and Safety of Fishery Class 1 Aceh. This study used a descriptive analytic and the conventional method where the sampling was done by a stratified random sampling method. Further, bacteria was isolated, the morphological of bacteria were observeted, pure cultures included Gram staining, catalase test, test oxidase, biochemical tests include tests Triple Sugar Iron Agar (TSIA), test Lysine Iron Agar (LIA), test citrate, test urea, test Oxidation / fermentative (O/F), Methyl Red test Vogue Proskuer (MRVP), carbohydrate fermentation test, test Motility Indol Ornithine (MIO) and the reading of the identification results were conducted. The result showed that three samples of African catfish from concrete pond, were positive infected with 100% prevalance attacked by Aeromonas hydrophila. Keywords: identification, Aeromonas hydrophila, African catfish, microbiology test. ABSTRAK Penelitian ini bertujuan untuk mengidentifikasi serta prevalensi bakteri Aeromonas hydrophila yang menyerang ikan lele dumbo yang dibudidayakan di Kabupaten Aceh Besar dengan uji mikrobiologi. Penelitian ini dilakukan pada bulan Maret 2016. Pengambilan sampel dilakukan pada Kecamatan yang terdata memiliki ikan lele dumbo di Kabupaten Aceh Besar yaitu Kecamatan Baitussalam. Pengamatan bakteri dilakukan di Laboratorium Bakteri Karantina Ikan Pengendalian Mutu dan Keamanan Hasil Perikanan Kelas 1 Aceh. Penelitian ini menggunakan deskriptif analitik dan metode konvensional dimana pengambilan sampel dilakukan dengan metode pengambilan acak terstratifikasi. Selanjutnya dilakukan isolasi bakteri, pengamatan morfologi, kultur murni meliputi uji Gram, uji katalase, uji oksidase, uji biokimia meliputi uji Triple Sugar Iron Agar (TSIA), uji Lysine Iron Agar (LIA), uji sitrat, uji urea, uji Oksidasi/Fermentatif (O/F), uji Methyl Red Vogue Proskuer (MRVP), uji fermentasi karbohidrat, uji Motility Indol Ornithin (MIO), dan pembacaan hasil identifikasi. Hasil penelitian menunjukkan bahwa 3 sampel ikan lele dumbo dari kolam beton positif terinfeksi bakteri Aeromonas hydrophila dengan prevalensi yang menyerang ikan lele dumbo kolam beton 100%. Kata kunci : identifikasi, Aeromonas hydrophila, ikan lele dumbo, uji mikrobiologi.