Effects of dietary ß-glucans on the productive performance, blood parameters, and intestinal microbiota of angelfish (Pterophyllum scalare) juveniles.

Among the potential feed additives, ß-glucans are known to positively affect the growth performance, blood parameters, and intestinal microbiota of fish, even the ornamental species. Therefore, the present study evaluated the effects of the dietary supplementation of different Saccharomyces cerevisiae ß-glucans concentrations (0, 0.05, 0.1, and 0.2%) in juvenile angelfish (Pterophyllum scalare) over a 42-day period. Regarding growth performance, no effects were observed on most parameters. However, 0.2% ß-glucans supplementation produced higher condition factor values, indicating a better nutritional status. Furthermore, ß-glucans supplementation did not affect blood parameters. Regarding intestinal microbiota, ß-glucans supplementation increased the abundance of the potentially beneficial bacterial genus Phascolarctobacterium. The high abundance of bacteria from the phylum Bacteroidetes, which can degrade ß-glucans, may be attributed to the increased abundance of Phascolarctobacterium spp. In addition, 0.2% ß-glucans supplementation produced more operational taxonomic units and higher Sobs (observed species richness), indicating effects on the overall bacterial community structure. These results demonstrate the potential application of ß-glucans as a dietary supplement to improve the performance and modulate the intestinal microbiota of angelfish.

Structure and genetic variability of golden mussel (Limnoperna fortunei) populations from Brazilian reservoirs.

The golden mussel, Limnoperna fortunei a highly invasive species in Brazil, has generated productive, economical, and biological impacts. To evaluate genetic structure and variability of L. fortunei populations present in fish farms in the reservoirs of Canoas I (CANFF), Rosana (ROSFF), and Capivara (CAPFF) (Paranapanema River, Paraná, Brazil), eight microsatellite loci were amplified. Five of those eight loci resulted in 38 alleles. The observed heterozygosity (Ho) was lower than the expected heterozygosity (He) in all populations, with a deviation from the Hardy-Weinberg equilibrium (HWE). The average value for the inbreeding coefficient (Fis) was positive and significative for all populations. There was higher genetic variability within populations than among them. The fixation index (Fst) showed a small genetic variability among these populations. The occurrence of gene flow was identified in all populations, along with the lack of a recent bottleneck effect. The clustering analysis yielded K = 2, with genetic similarity between the three populations. The results demonstrate low genetic structure and suggest a founding population with greater genetic variability (ROSFF). Our data point to the possible dispersal of L. fortunei aided by anthropic factors in the upstream direction. It was concluded that the three populations presented a unique genetic pool for Paranapanema River, with occurrence of gene flow.