This study aimed to evaluate the contribution of three diatom species on the lipid content of bioflocs, their permanence on the bioflocs and influence on the growth performance of juvenile shrimps. Juveniles of Litopenaeus vannamei were reared (30 days; three replicates per treatment) in biofloc systems inoculated with diatoms Amphora coffeaeformis (A), Cylindrotheca closterium (C), Conticribra weissflogii (W), or biofloc only (BF, chlorophycean rich). Water quality parameters were monitored daily and the microbiota on days 1, 10, 20 and 30. The lipid content and fatty acid profiles of bioflocs were analyzed at the end of the experiment. Shrimp survival rate (99%) at treatment A was significantly higher than at BF. The bioflocs in A treatment presented the highest lipid content, differing significantly from BF and W. The content of EPA (20:5) (n-3) was significantly higher in A and lower in BF, while linoleic acid (18:2) (n-6) was significantly higher in BF. The results indicate that high cell density of diatoms can be successfully maintained with silicate addition in biofloc systems and that the pennate A. coffeaeformis and the centric C. weissflogii are potentially better suited than the pennate C. closterium as food supplements for shrimp diets in biofloc nurseries system.

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The use of anesthetics in aquaculture ensures better animal welfare and survival during transport and the production cycle. The present study evaluated the anesthetic efficacy of essential oils (EOs) of Lippia alba (EOLA) and Ocimum gratissimum (EOOG) for pink shrimp Farfantepenaeus paulensis, and EOs of Origanum majorana (EOO) and Cymbopogon citratus (EOC) for white shrimp Litopenaeus vannamei. shrimp were exposed to (i) 500, 750 or 1000 µL L-1 of EOLA or (ii) 50, 100, 150 or 250 µL L-1 of EOOG, and L. vannamei were exposed to (iii) 150, 300 or 500 µL L-1 of EOC or (iv) 400 or 800 µL L-1 of EOO. The induction times were concentration dependent, with a decrease in induction time with the increase of the EOs concentration, but for EOLA, this pattern was observed only for anesthesia. Induction times for sedation and anesthesia were significantly shorter for shrimp exposed to EOC and EOO. The highest concentration of EOOG (250 µL L-1) resulted in 30% mortality. The recovery time was significantly longer for shrimp exposed to 800 µL L-1 of EOO compared to the other EOs. Overall, the action of EOs significantly differed between the two shrimp species. In conclusion, the tested EOs effectively anesthetized F. paulensis and L. vannamei.

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Probiotics are defined as live microbial supplements that benefit the host (Fuller, 1989). In aquaculture, the definition is more comprehensive due to the fact that probiotics are applied by different means, such as feeding, injection or immersion in the culture water. Research on the use of probiotics in animal husbandry has increased with the increasing demands for environmentally sound agriculture/aquaculture practices and safer food (Liu & Han, 2004), especially when substituting antibiotics and growth promoters (Akhter et al., 2015).Fish gastrointestinal tract probiotics play an important role in improving zootechnical performance, ingredient digestibility, disease resistance and immune system responses (Mello et al., 2013;Silva et al., 2015). Furthermore, direct probiotic addition to fish farming water can result in several effects, with two main advantages, namely the ability to control water quality by bioremediation and pathogen biocontrol through antagonistic effects (Jahangiri & Esteban, 2018;Liu & Han, 2004).Studies on aquaculture-applied probiotics are of great interest in the aquaculture industry and market, and several options are