Elucidating the Effect of Dietary Laminarin on Striped Catfish (Pangasianodon hypophthalmus) Growth Performance, Histological Features, Immune-Antioxidant-Related Genes, and Resistance to Aeromonas hydrophila Infection.

Laminarin (LAM) contains immunostimulants and antioxidative macromolecules that help aquatic creatures function and stay healthy. In this regard, striped catfish (Pangasianodon hypophthalmus) with an initial weight of 21.66 ± 1.24 g for each fish and 15 fish per aquarium were placed in 24 glass aquariums (90 L each). Fish fed with LAM at 0, 200, 400, and 600 mg kg represented as (L0, L1, L2, and L3) for 60 days were subsequently challenged with Aeromonas hydrophila. The findings demonstrated that the fish-administered dietary laminarin (DLAM) significantly (P < 0.001) boosted growth performance, intestinal health, and blood indices, particularly in fish-fed LAM at 400 and 600 mg kg. In comparison to the control group, the fish-fed DLAM displayed a significant (P < 0.001) decrease in MDA value and a rise in antioxidant (SOD, GPx, and CAT) and immunological indices (Lysozyme activity, phagocytic activity, and Complement C3), particularly with higher LAM doses. When compared to other groups, fish fed LAM at 400 and 600 mg kg diet showed increased significant (P < 0.001) levels of SOD, GPx, and CAT genes, while HSP70, IL-1β, and TNF gene expression decreased. According to the histological study, all tissues assessed in fish fed with LAM showed intact structural improvements with increasing DLAM supplementation. Following an A. hydrophila infection challenge, fish groups fed DLAM, specifically 600 mg kg, had significantly better survival rates than fish in the control group. As a result, the study found that the study found that striped catfish require 247.6 to 458 mg kg of DLAM to exhibit optimal growth performance, blood indices, antioxidative, immunological response, and infection resistance.