Existem anestésicos efetivos para peixes, mas é importante buscar alternativas de substâncias de fácil aquisição e baixo custo aos piscicultores e que não ofereçam riscos à saúde aos animais e manipuladores. Por se tratar de um produto de origem natural, ainda por possuir efeitos positivos a anestesia de peixes, vários estudos são conduzidos para investigar os efeitos de extratos vegetais, como óleos essenciais em diferentes procedimentos de manejo na aquicultura, obtendo‐se resultados promissores. Estudos sobre a viabilidade econômica do plantio, extração e comercialização do óleo essencial devem ser realizados, bem como testes e avaliações em diferentes organismos aquáticos. Essa revisão trata das propriedades anestésicas dos óleos essenciais de Lippia alba e L. sidoides em aquicultura.

Tilapia is one of the most important aquaculture species due to the desirable characteristics as easy reproduction and quick growth in several farming systems, including the recirculating aquaculture systems RAS. In this, the high flow of water to remove waste casually stimulates the fish to swim backset, and growth performance may be improved. Increasing the speed of swimming can improve performance within certain limits, in which however if exceeded can be harmful. Fish may be exhausted leading to impaired growth or even mortality. The objective of this work was to evaluate the growth performance of tilapia juveniles under sustained swimming exercise at different speeds. Additionally, the fish stocking density effect was tested in the sustained swimming exercise condition. In the first experiment, Nile tilapia juveniles were submitted in triplicates to sustained swimming exercise in speeds of control (not exercised), 1 BL/s (body length per second), 1.5 BL/s and 2 BL/s. In the second experiment, two fish stocking densities were tested in triplicates in sustained swimming exercise in speed of 2 BL/s and control not exercised. Fish growth performance was improved by sustained swimming exercise in speeds up to 2 BL/s. No expressive fish mortalities were observed in both experiments. The comparison between the two stocking densities does not allow us to safely say tilapia can be reared at stocking densities in order of 1,000 fish/m3, even under sustained swimming exercise. Other densities need to be tested.

The determination of nutritional requirements, based on diets administered in practice, considers physiological specificities and sustainability are essential to the development of suitable aquaculture technologies for novel fish species. The growth of jundiá (Rhamdia quelen Quoy and Gaimard) juveniles (31.54 ± 4.92 g) fed five diets comprising increasing levels of digestible protein (DP: 24, 29, 34, 39, and 44 %) and digestible energy (DE: 12.13, 13.39, 13.81, 14.64, and 15.06 MJ kg−1) with DP:DE ratios: 20, 22, 25, 27, and 29 g MJ−1, respectively, was evaluated. Each diet was fed to three groups of 25 fish for 75 days. Regression analysis showed that the different DP:DE ratios affected both growth and economic performance as well as excretion of total ammonia nitrogen. Fish fed diets with DP:DE ratios between 22 and 27 g MJ−1 achieved a higher daily weight gain, superior apparent net protein utilization, feed conversion rates, and lower feed costs. For the economically viable and environmentally friendly farming of jundiá juveniles in the initial grow–out stage (30 to 80 g average weight), the best DP:DE ratio was 25 g MJ−1 DP:DE (34.05 % DP and 13.81 MJ kg−1 DE).

Fish-processing residues represent a significant environmental challenge due to their high moisture and nitrogen contents, which favor greenhouse gas (GHG) emissions during degradation. This study evaluated how different waste management strategies affect GHG emissions from fish waste, including conventional composting (Bulk), composting amended with biochar (BulkBioch), burial with soil (S), and burial with soil plus sawdust (BulkS). Daily emissions of CH₄, N₂O, and CO₂ were monitored, and cumulative emissions were modeled using generalized additive models. Composting treatments (Bulk and BulkBioch) released higher CO₂, suggesting greater microbial degradation, while burial treatments developed earlier anaerobic conditions with reduced decomposition efficiency. Bulk showed the highest cumulative CH₄ and CO₂ emissions, whereas N₂O fluxes were greater in burial methods, reaching 2.18 g N₂O kg⁻¹ TS in S. Biochar addition was associated with 15% and 10% lower CH₄ and N₂O emissions, respectively, and earlier stabilization of CH4 emissions. In global warming potential, BulkBioch presented the lowest climate impact (305 g CO₂-eq kg⁻¹ fish), followed by Bulk (338 g CO₂-eq kg⁻¹), whereas BulkS reached up to 599 g CO₂-eq kg⁻¹. The use of bulking agents in burial resulted in lower CH₄ buildup and greater nutrient retention. Overall, combining bulking agents and biochar may represent a promising strategy to mitigate GHG emissions while supporting nutrient conservation.