This study aimed to assess the effects of dietary Cyanus depressus (CD) extract on rainbow trout (Oncorhynchus mykiss) physiology and health. Fish with an average weight of 3.29 ± 0.34 g were allocated to four feeding groups, receiving diets containing CD extract at doses of 0 (Control), 0.5 (CD05), 1 (CD1), and 2 (CD2) g kg⁻¹ for a period of 60 days. Results revealed significant improvements in final body weight, weight gain, and specific growth rate in groups supplemented with 1 and 2 g/kg of CD extract. Lipase activity increased notably in fish fed with CD0.5, CD1, and CD2 diets. The CD1 group exhibited the highest trypsin activity, while the groups receiving 1 g/kg and 2 g/kg of CD extract displayed the highest amylase activity. Analysis of gene expression levels for superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) showed marked increases across all groups compared to the control, with the most significant enhancement observed in fish fed with 2 g/kg of CD extract. Significant variations were observed in the expression of immunity-related genes among the treatments, with the highest expression levels of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) found in groups fed a diet enriched with CD extract. The increased activity of immune-related genes was more prominent in fish fed 2 g/kg of CD extract than in the control group. Notably, in fish fed with CD extract, heat shock protein 70 (HSP70) gene expression increased in the CD2 group, decreased in the CD05 group, and remained statistically unchanged in the CD1 group compared to the control. Additionally, supplementation with CD extract altered the composition and abundance of the intestinal microbiota in rainbow trout. In conclusion, our study suggests that Cyanusdepressus extract has significant potential for enhancing various physiological and health aspects of rainbow trout, particularly when supplemented at 2 g/kg.

Dissolved oxygen (DO) is a vital parameter in intensive rainbow trout aquaculture, directly influencing fish growth, health, and survival. As such, accurate monitoring and prediction of DO levels are crucial for ensuring sustainable and efficient aquaculture practices. This study assessed and compared the predictive performance of four machine learning algorithms Multivariate Adaptive Regression Splines (MARS), Random Forest (RF), Extreme Gradient Boosting (XGBoost), and Averaged Neural Networks (avNNet) in estimating DO concentrations based on a range of water quality parameters. A total of 120 samples were collected from 12 rainbow trout farms across Türkiye. The input variables included suspended solids, electrical conductivity, turbidity, nitrate, nitrite, ammonia, ammonium, orthophosphate, pH, water temperature, and total phosphorus. DO levels ranged between 8 and 15 mg/L. Model performance was evaluated using Mean Absolute Error (MAE), Root Mean Square Error (RMSE), Mean Absolute Percent Error (MAPE), and the coefficient of determination (R²). All models demonstrated strong predictive accuracy, with XGBoost achieving the best overall performance (MAE: 0.44, RMSE: 0.58, MAPE: 0.04, R²: 0.78), followed by RF, avNNet, and MARS. These findings highlight XGBoost as a robust predictor of dissolved oxygen levels in aquaculture systems, which may contribute to improving water quality management and increasing productivity in rainbow trout aquaculture.

The objective of the present study is to analyze the growth performance of rainbow trout (Oncorhynchus mykiss) (G) and brown trout (Salmo trutta ssp) (K) monoculture and polyculture in 75-25%, 66-34% and 50-50% stocking rates and its effects on food utilization and to determine the results with respect to aquaculture. Stocking was conducted in 5 different ratios in the study and each different stocking ratio was considered as a group and 24 fish were used in each group. Study groups were named based on stocking ratio percentages as G, K, G75K25, G66K34 and G50K50 and the study lasted 80 days. When the growth parameters in polycultures of rainbow trout and brown trout are considered, it was determined that the growth rates were not statistically different between rainbow trout monoculture and rainbow trout G75K25 and G50K50 groups, however rainbow trout in G66K34 experienced statistically significantly less growth when compared to others (p<0.05). Growth parameters of brown trout in polycultures demonstrated that the best growth was observed in G66K34 polyculture group (p<0.05). Study results showed that there was no significant difference between the groups based on food conversion coefficients and survival rates (p>0.05). As a result, it was determined that brown trout monoculture was the most advantegous group followed by G50K50 polyculture group, and when ecological and environmental parameters are concerned, G75K25 group, which consumed statistically significantly less food and demonstrated a lower food conversion ratio, would be more beneficial, and for fish breeders, who would like to increase the growth rate of the trout, G66K34 polyculture group would be more useful when compared to brown trout monoculture.

His study investigates the effects of dietary gallic acid (GA) supplementation on growth performance and the expression of genes linked to antioxidant, stress, and immune functions in rainbow trout (Oncorhynchus mykiss). Fish with an average body weight of 2.84 ± 0.25 g were fed diets containing 0 mg/kg (control), 300 mg/kg (G300), 450 mg/kg (G450), and 600 mg/kg (G600) of GA over 60 days. The results revealed significant improvements in growth indices, including weight gain, specific growth rate, and feed conversion ratio, in GA-supplemented groups compared to the control (P<0.05). At the molecular level, GA supplementation significantly upregulated the expression of antioxidant-related genes (SOD, CAT, GPX), stress-related genes (HSP70), and immune-related genes (TNF-α, IL-1β). The G300 group consistently exhibited the most pronounced transcriptional responses, while higher doses (G450 and G600) showed diminished or inconsistent effects. These findings suggest that a dietary inclusion of 300 mg/kg GA optimally enhances fish health and productivity by modulating key molecular pathways. This dosage is recommended as an effective feed additive for improving the performance and resilience of rainbow trout in aquaculture.