The walking catfish ( Clarias batrachus ) is well-suited for culture in warm climates and serves as an affordable food source in local markets. However, intensive aquaculture practices often face disease outbreaks, leading to substantial economic losses. While antibiotics, vaccines, and synthetic immunostimulants are commonly used for disease control, their application may pose risks to consumers and the environment. As an alternative, the medicinal plant Achyranthes aspera , widely found as a weed in India, offers an eco-friendly, sustainable, and cost-effective means of enhancing fish immunity. This study evaluated the effects of A. aspera leaf- and seed-supplemented diets on the growth and health performance of Clarias batrachus reared under pond conditions and experimentally challenged with Aeromonas hydrophila.
An 85-day feeding trial was conducted in hapas (2.0 m × 1.5 m × 1.5 m) placed within a pond at the ICAR–Central Institute of Fisheries Education, Rohtak Centre, Haryana, India. Juvenile fish (0.51 ± 0.032 g) were fed three experimental diets: 0.5% A. aspera seeds (D1), 0.5% A. aspera leaves (D2), and a control diet without plant ingredients (D3). Following the feeding trial, all fish (except the sham control group) were challenged intraperitoneally with 200 µl of virulent Aeromonas hydrophila (5 × 10⁶ cells/ml). The sham control group was injected with 200 µl of PBS (pH 7.4). Each treatment was conducted in triplicate.
Following the challenge test, mortality was monitored for seven days, after which blood and tissue samples were collected for biochemical analyses. Fish fed the D1 diet showed significantly (P < 0.05) higher average weight and specific growth rate, and lower feed conversion ratio and cumulative mortality compared to D2 and D3. Immune parameters, including serum lysozyme, myeloperoxidase, nitric oxide synthase, and hemagglutination titer, were significantly elevated (P < 0.05), while oxidative stress markers (TBARS and carbonyl protein) were significantly reduced (P < 0.05) in D1, followed by D2 and D3. Moreover, the expression of immune- and apoptosis-related genes (iNOS, SOD-C, NF-κB, Bcl-2, BAX, Cytochrome-c, Caspase-9, and Caspase-3) was upregulated in the liver and head kidney of fish fed experimental diets compared to the control.
A. aspera seed- and leaf-enriched diets clearly enhance the innate immunity of fish and contribute significantly to programmed cell death via both intrinsic and extrinsic pathways.