This study aimed to investigate the effects of the probiotic Betaplus^® and prebiotic Technomos^® as feed additives for Nile tilapia in terms of growth performance, health profiles, and resistance to infection with Aeromonas hydrophila and Pseudomonas fluorescens. A total of 960 healthy juvenile Nile tilapia (1.5 ± 0.01 g) were randomly divided into four experimental variants with three replicates for each variant. Fish were fed a commercial diet (control group, V₀), supplemented with BetaPlus^® probiotics–1% × BW (V₁), TechnoMos^® prebiotics–1% × BW (V₂), and with BetaPlus^® probiotics and TechnoMos^® prebiotics in a ratio of 1:1% × BW (V₃). Results on growth performance showed the best values in the probiotic variant, correlated with the health profile and the relative survival percentage after the challenge test with A. hydrophila and P. fluorescens. Similarly, the effects of dietary supplementation with probiotics and prebiotics on physiological conditions also recorded beneficial results in the synbiotic variant, where a high survival percentage was obtained after infection with the two pathogenic bacteria. In conclusion, the results of this study indicate that dietary supplementation with feed additives consisting of mentioned probiotics, prebiotic, and their combination as synbiotics has the potential to promote growth performance, improving tilapia immunity and increasing survival after the challenge test.

This study aimed to evaluate the growth, mortality parameters, and exploitation rate of Pontic shad, Alosa immaculata Benett, 1835, in the Danube River, Romania (km 169–197). The sampling collection started with the first signs of Pontic shad migration, on 4 March 2023, and continued weekly until the beginning of June 2023, when the last specimens were caught in the nets. The estimation of the growth, mortality parameters, and exploitation rate was done in FiSAT (FAO-ICLARM Stock Assessment Tools). The von Bertalanffy growth equation was estimated at L_∞ = 36.75 cm, the growth coefficient was k = 0.68 year⁻¹, and the theoretical initial age was t₀ = −0.67 year⁻¹. The total mortality rate (Z) estimated was 2.76 year⁻¹, with a natural mortality rate (M) and fishing mortality rate (F) of 0.89 year⁻¹ and 1.87 year⁻¹, respectively. The Z/k ratio was found to be 4.11 and the exploitation rate (E) was estimated at 0.68 year⁻¹, indicating the overexploitation of Alosa immaculata stocks. In conclusion, this study provides valuable insights into the population dynamics of Pontic shad in the Danube River, Romania. The assessments of the growth parameters, mortality rates, and exploitation rates highlight a level of overexploitation of Alosa immaculata stocks. These findings underscore the importance of applying effective fishery management strategies to ensure the sustainability and conservation of this valuable fish species in the Danube River ecosystem.