This study investigated the ethanolic leaf extract of Brazilian pepper tree (Schinus terebinthifolius Raddi) for its metabolite composition and effects on growth performance and intestinal immune gene expression in Nile tilapia (Oreochromis niloticus). Ultra-performance liquid chromatography-electrospray ionization-mass spectrometry (UPLC-ESI-MS/MS) in positive and negative modes revealed a diverse profile of 33 peaks in each polarity, identifying key compounds such as phenolic acids (e.g., gallic acid and ferulic acid), flavonoids (e.g., myricetin-O-glucoside and quercetin 3-O-glucoside), gallotannins (e.g., glucogallin and pentagalloylglucose), and triterpenoids (e.g., masticadienoic acid). A 60-day feeding trial with four groups (control and three extract doses; 0.5%; T0.5%, 1%; T1% and 2%; T2%) demonstrated dose-dependent enhancements in growth metrics, where final body weight increased by up to 106.9 ± 3.6 g, weight gain% by 197.3 ± 3.5%, and the growth rate got more than doubled in T2% (2.4 ± 0.1), alongside improved feed conversion ratio (1.24 ± 0.01) at 30 days and condition factor (stabilized at 2.1 ± 0.0) at 60 days post-feeding. Viscero- and gastro-somatic indices declined insignificantly in most feed groups, indicating improved muscle growth. Biphasic patterns were observed in intestinal gene expression as follows: over 60 days, the IL-1β gene upregulated at low doses but returned to normal at high doses. The IL-10 gene upregulated progressively, promoting an anti-inflammatory balance. In fish fed medium and high doses (T1% and T2%), the IgM gene is upregulated, supporting humoral immunity. These outcomes, linked to the extract’s previously described antioxidants, anti-inflammatory, and antimicrobial bioactive compounds, suggest that S. terebinthifolius is a promising natural feed additive for sustainable tilapia aquaculture and warrants further validation for commercial application.

This study evaluated graded dietary doses of Saccharomyces cerevisiae postbiotic (0, 1.25, 2.5 and 5 g kg⁻¹) on growth, feed utilization, serum biochemistry, expression of IGF-1, SOD2, IL-1β, IL-10 and IgM, and resistance to Fusarium oxysporum in Nile tilapia (Oreochromis niloticus; 35.1 ± 0.9 g) after 30 and 60 days of feeding. Although the 5 g Kg⁻¹ inclusion significantly increased WG (59.4 ± 0.9) and SGR (1.5 ± 0.0) and decreased FCR (0.8 ± 0.0), significant positive effects on multiple endpoints were also recorded at 1.25 and 2.5 g/kg. Serum total protein and globulin rose with increasing dose and feeding duration, while albumin showed limited change, lowering the A/G ratio. AST remained unchanged. Creatinine and glucose declined with postbiotic supplementation; the glucose reduction effect was dose-dependent, whereas creatinine was unaffected by feeding duration. The highest gene expression of hepatic IGF-1, SOD2, IL-1β, and IL-10 and splenic IL-1β, IL-10, and IgM was in T3 at both checkpoints; however, the highest gene expression of intestinal IL-1β, IL-10, and IgM expression was in T1 at both time points. The pathogenicity experiment showed a significant survival against F. oxysporum (p < 0.0001) compared to controls. The results suggested that dietary S. cerevisiae postbiotic improved growth, biochemical and molecular responses, and survival of Nile tilapia against F. oxysporum.

Amirthalingamia macracantha (Joyeux and Baer, 1935) larvae, a member of the Gryporhynchidae family (Cestoda: Cyclophyllidea), are commonly found in a variety of African fish species, including Nile tilapia (Oreochromis niloticus, Linnaeus, 1758). Nonetheless, little is known regarding their existence in native Egyptian fish species. Two hundred O. niloticus were examined in the current investigation, using standard parasitological techniques to detect the presence of these larvae in different fish organs. According to this study’s findings, A. macracantha larvae were found in 35% of the microscopically examined samples as red nodules, attaching to the serosa of both the anterior and posterior sections of the intestine and stomach, respectively. The mean abundance of the infection was 3.5 ± 0.05 (CI 95% 3.4–3.5), and its mean intensity was 10 ± 1.7 (CI 95% 8.2–11.7). The existence of two rows of twenty rostellar hooks of varying lengths is the main characteristic of the parasite. The upper row consisted of four large hooks and six smaller ones, while the lower row contained smaller hooks of consistent length. According to histopathological analysis, the larvae with a hook-and-spiny rostellum were affixed to the stomach serosa of O. niloticus. Additionally, there was a notable presence of degranulated mast cells and lymphocytes of varying sizes within the stomach’s lamina propria, submucosa, and blood vessels, as well as a loss of gastric epithelium, fibrosis, and enlargement of submucosal lymph vessels. This study offers a succinct description of this larval stage, representing the first reported occurrence of its presence in Egyptian O. niloticus.