The production of ornamental fishes has been intensified to attend the global market. With this expansion, an increase in infections and infirmities has been observed, most of which are attributed to pathogenic bacteria. Dietary supplements to improve growth and immunity of these animals have been introduced as a safe way to control and prevent disease outbreaks. This study therefore aims to isolate, identify, select and evaluate strains of lactic acid bacteria that show potential as probiotics for Pterophyllum scalare. Of 16 initial isolates, five strains were molecularly identified as Enterococcus faecium. Profiles of probiotic candidate strains were based on: catalase test and hemolytic activity; in vitro tolerance responses to NaCl (0.5; 1.0; 1.5; 2.0; 2.5 and 3.0%), pH (4, 5, 6, 8, and 9), and bile salts (5%); pathogen inhibition halo size maximum growth rate; and final counts of viable cells. In vivo effectiveness of the best performing strain in vitro was determined by growth and survival parameters for post-larvae over a period of 40 days. All strains fulfilled the criteria as probiotics in animals, with Strain 4 showing the best results in vitro, and improving growth and viability of fish in vivo.