ABSTRAK

Pengendalian hama dan penyakit merupakan salah satu faktor pendukung optimalisasi budidaya intensif ikan lele dumbo (Clarias gariepinus). Infeksi Motile Aeromonas Septicemia (MAS) pada ikan lele dumbo yang dapat menyebabkan kematian disebabkan oleh bakteri A.hydrophila. Penelitian ini bertujuan untuk menganalisis gejala klinis, mortalitas dan rerata waktu kematian (RWK) ikan lele dumbo (Clarias gariepinus) akibat infeksi bakteri Aeromonas hydrophila sebagai causative agent selama uji Postulat Koch. Penelitian ini menggunakan metode deskriptif dan eksperimental dengan Rancangan Acak Kelompok (RAK) 9 isolat bakteri dengan tiga ulangan,sehingga dihasilkan 27 unit percobaan. Isolat bakteri diperoleh dari ikan patin (Pangasius sp) terinfeksi asal BPBAT Mandiangin. Infeksi bakteri secara intraperitoneal dosis 0,1 ml/ikan, kepadatan suspensi bakteri 108 sel/ml pada 54 ekor ikan uji, diamati gejala klinis, mortalitas dan waktu kematian dalam menit selama 3 hari. Gejala klinis eksternal yaitu dropsy termasuk gripis sirip, adanya borok pada APMG-2 sedangkan gejala internal insang, hati dan ginjal pucat. Berdasarkan identifikasi kultur 27 isolat bakteri mengarah pada karakteristik A.hydrophila. Persentase mortalitas ikan di semua unit percobaan sebesar 50%. Rerata waktu kematian (RWK) tercepat diperoleh pada isolat APMG-2 sebesar 1687,3 ± 174,8 menit diikuti oleh APMG-6, APMG-10, dan APMG-8. Isolat APMG-7 memiliki nilai RWK tertinggi yaitu 2138,7 ± 790,4 menit, yang juga menunjukkan standar deviasi terbesar dibandingkan isolat lainnya. Hal ini mengindikasikan adanya perbedaan virulensi antar isolat A. hydrophila. Meskipun uji statistik tidak dapat dilakukan karena jumlah ulangan terbatas, pola deskriptif RWK dan visualisasi gejala klinis memperkuat simpulan bahwa isolat APMG-2 merupakan kelompok yang paling patogen. Saran penelitian lanjutan dengan menambah replikasi dan sampel, pengujian molekuler isolat dan uji histopatologi untuk memperkuat analisis virulensi.

Kata Kunci: Lele dumbo, Aeromonas hydrophila, Postulat Koch

                                                                            ABSTRACT

Pest and disease control is crucial in optimizing intensive African catfish aquaculture (Clarias gariepinus). Motile Aeromonas Septicemia (MAS), a lethal infection in catfish, is caused by Aeromonas hydrophila. This study aimed to analyze the clinical signs, mortality, and mean time to death (MTD) of African catfish infected with A. hydrophila as the causative agent through Koch’s postulate testing. A descriptive and experimental approach was used with a Group Randomized Design (GRD) involving 9 bacterial isolates and 3 replicates, totaling 27 experimental units. The isolates were obtained from infected Pangasius sp. originating from BPBAT Mandiangin. Fish were infected via intraperitoneal injection with 0.1 ml per fish of a bacterial suspension containing 10? cells/ml, using 54 test fish. Clinical signs, mortality, and time of death (in minutes) were observed over 3 days. External symptoms included dropsy and frayed fins (fin rot), while internal signs included pale gills, liver, and kidneys. Ulcerative lesions were also observed in APMG-2 isolates. Bacterial culture identification from 27 isolates revealed morphological characteristics consistent with A. hydrophila. All experimental units showed a 50% mortality rate. The shortest MTD was recorded in isolate APMG-2 (1687.3 ± 174.8 minutes), followed by APMG-6, APMG-10, and APMG-8. The longest MTD was recorded in APMG-7 (2138.7 ± 790.4 minutes), which also displayed the highest standard deviation, indicating a slower and more inconsistent mortality pattern. These results suggest differing virulence levels among A. hydrophila isolates. Although statistical analysis could not be performed due to limited replicates, descriptive patterns in MTD and visualization of clinical signs support the conclusion that isolate APMG-2 is the most pathogenic. Future studies should include more replicates and sample size, molecular identification of isolates, and histopathological analyses to strengthen virulence assessment.

Keywords: Clarias gariepinus, Aeromonas hydrophila, Koch’s postulates