Kombucha–algae mediated selenium nanoparticles as dietary supplements for fresh-water fish feeding: growth, histological, and immunohistochemical responses

Abstract

This study evaluated the synthesis of kombucha–algae mediated selenium nanoparticles (KA-SeNPs) and their dietary effects on growth performance, histological and immunohistochemical indicators in Nile tilapia ( Oreochromis niloticus ). The nanoparticles were characterized by FTIR, UV–Vis spectroscopy, and TEM, revealing spherical particles with 58.3 nm average size. A 60-day feeding trial was conducted using two dietary treatments. Fish with an initial mean weight of 8.75 g were fed either a basal diet or a basal diet supplemented with KA-SeNPs at 0.5, 1.0 and 1.5 mL/kg. Growth performance indices, viscerosomatic index (VSI), hepatosomatic index (HSI), histological structure, morphometric parameters, and immunohistochemical responses were evaluated. Fish fed KA-SeNPs showed significantly improved weight gain and feed utilization efficiency compared to the control group, with lower VSI and HSI values. Histological examination of spleen, intestine, liver, and muscle tissues revealed improved tissue architecture. Morphometric analysis demonstrated increased melanomacrophage center density, intestinal villus length, goblet cell number, and myocyte diameter in the KA-SeNPs group. Immunohistochemical findings indicated enhanced expression of immune-related markers in splenic and intestinal tissues. These findings suggest that dietary KA-SeNPs supplementation is associated with improved growth performance and enhanced histo-immunological indicators in Nile tilapia. However, further studies are required to investigate the long-term effects and molecular mechanisms behind these benefits.