Feed and gut microbiota of African catfish ( <i>Clarias gariepinus</i> ) fed complementarity of fish and poultry-derived protein meals

This study investigated the effects of varying dietary inclusion levels of fishmeal (F) and blended poultry-derived protein meals (P), comprising poultry by-product meal, hydrolysed feather meal, and dried blood meal, on the microbial communities in both the feed and posterior intestine of African catfish (Clarias gariepinus). Juvenile fish (116.11 ± 0.98 g/fish) were fed four isonitrogenous (43%), isolipidic (12%), and isoenergetic (gross energy: 19 MJ/kg) diets for 84 days. The dietary treatments included HF-LP (high F, low P: F = 9.1%, p = 22.7%), MF-MP (moderate F, moderate P: F = 4.6%, p = 28.1%), HF-HP (F = 9.2%, p = 31.4%), and LF-HP (F = 1%, p = 39.2%). A total of 48 samples (12 feeds and 36 posterior intestinal digesta) were analysed using 16S rRNA amplicon sequencing. Dietary treatments had no significant effect on the overall microbial diversity and composition within the gastrointestinal tract of the catfish, including ACE index (p = 0.542), Shannon index (p = 0.542), and Simpson index (p = 0.601). Three taxa, Vibrio, Lactobacillus, and Weissella, were predominantly enriched in the feed, whereas Cetobacterium, Mycobacterium, and Reyranella were dominant in the intestinal microbiota. Although Clostridium, Fusobacterium, and Sphingomonas were detected in both the feed and intestinal samples, their relative abundance was consistently low (<5%). These findings contribute to a better understanding of the interactions between diet and gut microbiota in African catfish.