Effect of isolated bacteria and microalgae on the biofloc characteristics in the Pacific white shrimp culture

At present, the Pacific white shrimp Litopenaeus vannamei Boone, 1931, is one of the species with the greatest potential to be reared under biofloc Technology (BFT). Although BFT presents promising culture methods, some of these require improvements in efficiency by the use of native microalgae and bacteria (BFNO) as an alternative to commercial organism probiotics (BFCO). This experiment was developed using a culture system for the shrimp L. vannamei to a stocking density of 400 in./m3 for 44 days. Schizochytrium sp. and recently isolated Latobacillus plantarum (class: Bacilli), a probiotic strain (used as experimental biofloc), were incorporated to geomembrane tanks holding 28 m3 seawater to evaluate if these presented bioregulating effects influencing water quality and growth performance of L. vannamei. These microorganisms were compared with the BFCO. Results showed that both promoted bioflocs maintained optimal concentrations of total ammonium, nitrites, and nitrates for L. vannamei cultures. However, the BFCO required to be supplied every 10 days, whereas the experimental biofloc only required an initial stocking and maintenance of sodium carbonate levels >100 mg L−1 and pH > 7.5. Additionally, the load of Vibrio spp. in experimental biofloc was less than that observed for BFCO. Furthermore, the results of growth performance did not demonstrate differences between both treatments. Therefore, it is suggested that Schizochytrium sp. and the bacterial strain of L. plantarum should be used as initiator and basic constituents of the biofloc-based culture systems for L. vannamei, maintaining good water quality and avoiding periodical probiotic supplementation in cultures. Keywords: Induced biofloc, B. plantarum, L. vannamei, Microalga

Preliminary observations on Cichlasoma beani in culture conditions

The Mexican cichlid, Cichlasoma beani has potential to be a candidate for the aquarium trade and the food industry. However, currently there are no studies regarding the effect of environmental factors on the species in culture conditions. The aim of this study was to assess the potential of C. beani to be maintained in cultured conditions. Additionally, the fish were exposed to different temperatures to examine the effect of temperature on growth, condition and survival of cultured juveniles in 26, 28 and 30°C, for six weeks in recirculation systems. Fish were fed 2.4 mm pellets (40% protein, 15% fat) at a ration rate of 5% body weight per day (dry weight food: wet weight fish). An aggressive behavior in all treatments led to lowered survival, making it impossible to conclude that temperature had an effect on the recorded variables. However the results showed a tendency that indicated the final weight and specific growth rate at 30°C was greater than in 26 and 28°C, perhaps due to a better metabolism and nutrient assimilation