One of the challenges for the production process in fish farming is diseases, especially infectious diseases, resulting in lost productivity and economic losses. Numerous researchers have carried out the use of medicinal plants to treat fish diseases. This study aimed to evaluate the efficacy of Serapoh Chromolaena odorata leaf ethanolic extract in treating Vibrio alginolyticus-induced vibriosis in Asian Seabass Lates calcarifer using various frequencies and immersion times of the extract. The research examination involved a factorial completely randomized design in which immune response, survival rate, relative percent survival (RPS), and histopathology were evaluated as therapeutic efficacy markers.
The Asian Seabass (8.88±0.46 cm) was previously challenged with V. alginolyticus (107 CFU mL-1) intraperitoneally, up to 0.1 mL fish-1. As the therapeutic phase, Asian Seabass are immersed in an ethanol extract of serapoh leaves (86.3 mg L-1) with a combination of various immersion treatments in frequency (every 1, 2, and 3 days) and duration (15, 30, and 60 minutes) for seven days each. Blood samples were collected to evaluate lysozyme activity and respiratory burst before the challenge test (H-0); as well as on the second (H-2); fourth (H-4) and seventh (H-7) days after the challenge test. The survival score of Asian Seabass after the challenge test with V. alginolyticus was used to determine resistance and treatment efficacy against Asian Seabass was measured by the relative percent survival (RPS) at the end of treatment. Liver samples were collected for histopathology at the end of treatment.
The results showed that the interaction between the frequency and duration of immersion in Serapoh leaf ethanolic extract was able to stimulate the immune system components, resulting in improved immunological response and survival rate (80%) of Asian Seabass following the challenge test. Based on an RPS value of 60% (Table 1) the most effective immersion treatment for overcoming vibriosis in Asian Seabass is 30 minutes every two days (P2.30). Histopathological analysis revealed image changes in liver tissue, indicating that Serapoh leaf ethanolic extract improves the immunological response of Asian Seabass, reducing the pathogenicity of V. alginolyticus.