The effects of β-1,3/1,6-glucan on Hyphessobrycon eques were assessed after 42 days of feeding diets containing 0 (control group given commercial feed), 0.5, 1, or 2 g β-glucan/kg diet. In total, 180 fish, with an initial weight of 0.43?±?0.03 g, were used. There were 15 fish in each of twelve 42-L aquariums, and there were 3 aquariums of fish for each dietary treatment. The fish were fed until apparent satiety. Performance parameters (final weight, total length, standard length, feed intake, survival rate, weight gain, feed conversion, specific growth rate, and condition factor) and plasma glucose concentration were measured. Histological analysis of the proximal portion of the intestine (width and height of the villi, depth of the crypts, height of the enterocytes, thickness of the muscle layer, and number of goblet cells) was performed. Different levels of the additive did not influence fish performance (for example, final weight: control: 0.63 g, 0.5: 0.60, 1: 0.58, and 2: 0.61). Likewise, there was no influence on the plasma glucose concentration (control: 81.80 mg/dL, 0.5: 75.33, 1: 85.00, and 2: 81.00) and intestinal morphometry of the animals. However, the results showed that 2.0 g/kg of β-1,3/1,6-glucan provided a greater abundance of goblet cells secreting acidic and neutral mucus present in the epithelium (periodic acid-Schiff: 66.67 cells, Alcian blue pH 1.0: 72,67 cells, and Alcian blue pH 2.5: 95.00 cells), showing significant differences when compared to animals in the control group, which may represent better protection of the intestinal epithelium of H. eques.

The objective of the present work was to develop species-specific microsatellite markers for P. scalare and to analyze the diversity and genetic structure of a wild population, from the Amazon River, and three commercial stocks (common, marble, and clown morphological variants), from farmers in Vieras-Minas Gerais. Through microsatellite-enriched genetic libraries, 11 microsatellite markers with adequate amplification patterns were characterized. Population genetic analysis identified eight polymorphic loci that generated 66 alleles ranging from two alleles (PSCA1B3) to nine (PSCA2H1). The polymorphic information content ranged from 0.031 to 0.827. High genetic differentiation was observed between the wild population and the stocks, and moderate differentiation between the three stocks. Deviation in the Hardy-Weinberg equilibrium was observed in one locus in the wild population, in five loci in the common morphological variant, in two in the marble, and in two in the clown morphological variant. Bayesian analysis of genetic structure revealed the existence of two clusters, one represented by the natural population and the other by the stocks. The developed microsatellite markers serve as a tool for the analysis of diversity and genetic structure and conservation studies of P. scalare.