The objective of this work was to assess the time-related action of probiotic Lactobacillus plantarum in the bacterial microbiota of the digestive tract of Litopenaeus vannamei, and the relation of total haemocyte count and serum phenol oxidase activity of shrimp challenged with Vibrio harveyi. Shrimps were fed with a probiotic-supplemented diet, for eight days, then shifted to a commercial diet. Shrimps fed only with the commercial diet served as control. Evaluations were made on the 8th day of experiment and repeated two, four, six and eight days later. Total lactic bacteria in the digestive tract was higher until the 4th day of evaluation in the probiotic-supplemented group. Vibrio spp. counts were higher in the control at days zero and two. Until the 4th day of evaluation, the total haemocyte counts in shrimps after challenge with V. harveyi were higher in probiotic-supplemented group than in control group. Significant difference was not observed in phenol oxidase activity. On the 6th day after shifting from supplemented to control diet, all parameters were equal in both groups, suggesting that the time-related action of L. plantarum in shrimp is short.

O objetivo deste trabalho foi determinar o método de coleta de fezes mais adequado para camarões marinhos (Litopenaeus vannamei) na determinação do coeficiente de digestibilidade aparente da proteína bruta e da matéria seca de dietas comerciais, e avaliar o efeito da suplementação de Lactobacillus plantarum na dieta sobre o coeficiente de digestibilidade aparente da proteína, da energia e da matéria seca. Foram testados três sistemas de coletas de fezes: decantação, sifonamento e dissecação dos animais. A coleta por decantação foi o sistema mais adequado para a determinação in vivo dos coeficientes de digestibilidade aparente da proteína bruta e da matéria seca das dietas, por apresentar baixo grau de lixiviação das fezes e por ser de fácil execução. Nos camarões alimentados com a dieta suplementada com L. plantarum, foi observado maior coeficiente de digestibilidade aparente da proteína (84,18±0,35%) e da energia (81,28±0,16%), quando comparado ao grupo controle (82,73±1,01 e 78,63±0,93%, respectivamente). O uso de L. plantarum como aditivo probiótico na ração pode trazer benefícios nutricionais a L. vannamei, com melhor aproveitamento dos nutrientes.

To meet the growing demand for sustainable aquaculture, the biofloc technology (BFT) system has emerged as a promising solution, offering high productivity, improved water use efficiency, and enhanced environmental and biosecurity performance. Economic and risk analyses are essential tools for identifying the key technical and economic factors that determine the profitability and long-term sustainability of aquaculture systems. This study aimed to evaluate the economic feasibility and the risk associated with Nile tilapia juvenile production in a BFT system. Economic viability indicators were calculated using real data on capital investment, operational costs, and zootechnical performance from a production cycle. Scenario analyses were conducted to assess the effects of fluctuations in input prices and survival rates on overall economic outcomes. Stochastic simulations were also conducted to determine the probabilities of economic results. The items with the greatest impact on costs were the acquisition of the greenhouse and fingerlings, representing 27.64% of the initial investment and 33.24% of the operating cost, respectively. The BFT system showed a positive net margin and profitability per production cycle, with the exception of the pessimistic scenario. The risk analysis demonstrated that in 87.29% of the simulations resulted in a positive profit. Thus, the production of tilapia juveniles in a BFT system is an economically viable investment. However, its success is contingent upon specific technical and market conditions, underscoring the need for careful management and context-specific planning.

This study aimed to analyze the economic feasibility and the risk associated with the Nile tilapia juveniles cultured in a biofloc technology system. The indicators used in this study followed the operating cost criterion. Scenarios were analyzed in terms of variations in input prices and survival. Stochastic simulation were also carried out in order to determine the probabilities of economic results. The items with the greatest impact on costs were the acquisition of the greenhouse and fingerlings, which represented 27.64% (initial investment) and 33.24% (operating cost) respectively. The analysis showed that the biofloc technology system is viable in a short and long term, since it covered all the operational costs and showed a positive gross margin per production cycle, except in the pessimistic scenario. The risk analysis demonstrated that in 87.29% of the simulations obtained a positive profit. Thus, the tilapia juveniles production in biofloc technology system is a low-risk and economically viable investment.

This study aimed to evaluate the dynamics of total carbon (TC), total nitrogen (TN), total phosphorus (TP), and some indicators of environmental sustainability of Nile tilapia reared in a biofloc technology (BFT) system. Nile tilapia fingerlings were cultured in three BFT units of production (4.2 m³ each) at a stocking density of 395 fish/m³. After 70 days, the survival rate was 98.05%, with a final average weight of 20.43 g, and apparent feed conversion of 1.05. Nutrient inputs were from supply water, initial fish biomass, and feed; outputs were measured from the final fish biomass and effluent. TC, TN, and TP concentrations in the water increased linearly over time (p < 0.001) by 1.54, 1.66, and 0.44 mg/L, respectively. Feed contributed over 88% of nutrient inputs, while fish final biomass accounted for over 50% of output. Nutrient retention in fish final biomass was 29.74% (TC), 45.38% (TN), and 46.34% (TP). The system had low eutrophication potential, estimated at 57.39 kg TC, 20.02 kg TN, and 5.70 kg TP per ton of fish. Water use was 135.3 m³/ton, but energy demand was high (114.59 MJ/kg). The closed system reduces biodiversity risks by preventing fish escape. In conclusion, BFT supports high fish productivity with efficient nutrient use, minimal water use, and limited environmental impact, contributing to environmentally sustainable aquaculture.