Probiotic actions of Bacillus cereus var. toyoi and Saccharomyces boulardii in silver catfish (Rhamdia quelen) larvae culture

Abstract

The objective of this study was to evaluate the use of Bacillus cereus var. toyoi and Saccharomyces boulardii as probiotics to improve Rhamdia quelen culture. Six hundred larvaes (0.16±0.07 g) were divided in three replicate tanks (25-L recirculation, 20 ºC, photoperiod of 12 h light/12 h darkness) per treatment and were randomly assigned to the following treatments: Bacillus cereus var. toyoi; Saccharomyces boulardii; B. toyoi and S. boulardii; and control (without probiotic addition) for a period of 30 days. The fish were fed five times daily (56% crude protein - Supra alevino inicial®) and the probiotics were applied in water once a day. The doses of probiotics were <img src="/img/revistas/rbz/v41n3/aproximadamente.jpg">5 × 10(8) and <img src="/img/revistas/rbz/v41n3/aproximadamente.jpg">2 × 10(9) CFU (colony forming unit)/mL for B. cereus var. toyoi and S. boulardii, respectively. Both probiotics have an inhibitory effect in vitro against Vibrio carchariae and are able to grow in media prepared with fishery water; however, no effect was observed on growth parameters when they were administered to Rhamdia quelen larvae.