Immunogenic Effects of Dietary Terminalia arjuna Bark Powder in Labeo rohita, a Fish Model: Elucidated by an Integrated Biomarker Response Approach

SIMPLE SUMMARY: It is widely believed that aquaculture has the greatest potential to provide both economic and nutritional security. Bacterial infections in the culture system result from intensified aquaculture methods, resulting in a significant economic loss for fishermen. Because antibiotics are the standard treatment for bacterial infections in Southeastern countries, antimicrobial resistance has emerged as a major health concern. Herbal remedies are being promoted as a replacement for the undesired medicines. In Ayurveda, the Terminalia arjuna plant is considered a “miracle plant” since it has been used for centuries to treat serious illnesses in humans. However, applications in aquaculture remain in their early stage. The purpose of this study is to assess the therapeutic value of incorporating powdered Terminalia arjuna bark with Labeo rohita. Based on the findings, the researchers suggest adding Terminalia arjuna bark powder to fish food at a rate of 12.3 g·kg(−1) (as determined by the broken line regression equation) to help the fish become resistant to disease. ABSTRACT: Utilizing agro-industrial waste and herbal products to create a circular bioeconomy is becoming increasingly popular. Terminalia arjuna is a significant ethnomedicinal plant that has not yet been exploited in animal feed. In the present study, nutritional Terminalia arjuna bark powder-based fish feed was created and supplied to a candidate fish species Labeo rohita at varied levels: 0% (0 g/kg), 0.5% (5 g/kg), 1% (10 g/kg), and 1.5% (15 g/kg). These treatment groups are denoted as CT, T1, T2, and T3, respectively. Utilizing a contemporary comprehensive biomarker response strategy, the study clarified the genomic influence of dietary herb inclusion. In response to bacterial infection, the immunogenic genes, STAT 1 (signal transducer and activator of transcription 1), ISG 15 (interferon stimulating gene), and Mx “myxovirus resistance gene”, were shown to be elevated. The results of densitometry demonstrated a dose-dependent increase in STAT 1 and ISG 15, with Mx exhibiting maximal values at 1 g/kg TABP (Terminalia arjuna bark powder-based feed). This is the first study to identify TABP as an immunomodulator in fish and established the IBR (Integrated Bio-marker Response) as a reliable marker in evaluating the impact of multiple drivers in a holistic manner. Thus, the present study cleared the path for TABP to be utilized as an effective feed additive which enhances the specific adaptive immune system of the fish for the production of the Green fish product for a sustainable circular bioeconomy.