Effects of Dietary Indian <i>Sphagnum junghuhnianum</i> Peat Moss Pectin on Growth, Digestive Enzymes, Antioxidant Capacity, Immune Responses, and Disease Resistance in <i>Catla catla</i> Fingerlings

In this study, the effects of dietary supplementation of Indian Sphagnum junghuhnianum peat moss pectin were evaluated in Catla catla fingerlings. A total of 375 fish (10.47 ± 0.2 g) were randomly divided ( n = 25/tank) into basal diet (Sphagnum peat moss pectin [SPMP] at 0% control) (crude protein: 37%, crude fat: 8%) or four treatment diets, 2% (SPMP2), 4% (SPMP4), 8% (SPMP8), and 16% (SPMP16) for 60 days. The water temperature was 27.5 ± 0.6°C, and fish were fed with the experimental diets at 4% of their live body mass. The results of this research revealed that the SPMP8 diet substantially enhanced growth indices in catla fingerlings ( p &lt; 0.05). The highest and lowest whole‐body lipid levels were in SPMP8 (5.03%) and control (4.06%), respectively. The gut amylase activity was significantly higher in the SPMP8 group, while lipase and protease remained unchanged. Additionally, fish given 8% and 16% SPMP had a significant decrease in the liver’s malondialdehyde concentration. Superoxide dismutase (SOD) activity was increased in SPMP‐supplemented groups, with the highest value in group SPMP8 while catalase (CAT) activity was higher in SPMP4, SPMP8, and SPMP16 compared to the other groups. Supplementing the diet with 4%–16% SPMP increased the fish’s red blood cell count and hemoglobin level. An 8% SPMP diet increased white blood cell count, phagocytic activity, lysozyme, acid, and alkaline phosphatase (AKP) activities compared to the other groups. The cumulative mortality of fish after challenge with virulent Aeromonas hydrophila significantly decreased in SPMP8 and SPMP16 groups, compared to the other treatments. The results of this study indicated enhancements in immunological markers, specifically an increase in levels of AKP, SOD, and CAT. This research proposes that providing catla fingerlings with 8% SPMP effectively boosts their growth, immune response, and disease resistance.