Domickson Silva Costa

The use of residual biomass from industrial seaweed processing in aquafeeds may represent a potential route for the reuse of residual biomass within a circular-economy framework. This proof-of-concept trial evaluated the effects of dietary supplementation with wet solid residue from the seaweed Kappaphycus alvarezii in Mugil liza over 80 days under a mixed-feeding system. The treatments comprised nominal wet-residue levels corresponding to 0, 6, 12, 18, 24 and 30% of the reference daily feed intake, equivalent to 0, 0.7, 1.5, 2.2, 2.9 and 3.5% of the dietary mixture on a dry-matter basis, respectively. No mortality occurred, indicating no detectable adverse effects under the tested conditions. Haematological data indicated a pattern consistent with hormesis, with the 6% and 12% nominal wet-residue levels associated with increased erythropoietic responses. Intestinal integrity and fillet nutritional quality were preserved; however, eviscerated yield showed numerical variation among treatments, with the lowest median value observed at 18%. The mixed-feeding strategy allowed a reduction in commercial feed input without compromising growth. Overall, the tested nominal wet-residue levels, corresponding to 0.7–3.5% of the dietary mixture on a dry-matter basis, were not associated with detectable impairment of survival, intestinal integrity or fillet quality. Future studies should employ randomized designs with replicated experimental units to further explore the potential of using K. alvarezii processing residue as a partial replacement for traditional feed components in M. liza production.

This study aimed to evaluate the effects of a probiotic mix composed of Bacillus spp. and benzoic acid, all together and separately, in intestinal microbiology, liver, and intestinal histology, as well as in the composition of the intestinal microbiota by high-throughput sequencing analysis of juvenile Nile tilapias Oreochromis niloticus. Three hundred and twenty fish were divided into four experimental groups with four replicates. They were fed for 54 days: control (no supplementation), 0.1% benzoic acid (BA0.1%), mix of Bacillus spp. (Bacillus), and feed supplemented with Bacillus spp. and 0.1% benzoic acid (B+BA0.1%). Classical microbiological analysis showed that B+BA0.1% increased the concentration of total heterotrophic bacteria (4.94 ± 0.77) compared to the control group (4.43 ± 0.90). The results showed significant liver changes such as ballooning, congestion of large vessels, and pancreatic congestion between treatments B+BA0.1% and BA0.1%, the latter resulting in less (15.91 ± 16.61) pancreatic congestion than the other treatments. Vacuolation in the intestine was greater in supplemented animals with BA0.1%, B+BA0.1%, and Bacillus spp. than in the control group. The width of the villi was greater in the group supplemented with B+BA0.1% (22.19 ± 10.91) than in the Bacillus group. The abundance of Firmicutes and Bacteroidetes was higher in the B+BA0.1% group. Cetobacterium somerae was more abundant in the Bacillus and B+BA0.1% groups in the diversity index. Notably, joint supplementation with the probiotic mixture Bacillus spp. and 0.1% benzoic acid had a synergistic effect on the intestines of tilapia, positively modulating the intestinal microbiota.

Towards Sustainable Aquaculture: A Review on The Use of Microalgae as Functional Feed Ingredients

Hepatoprotective action of including açaí ( Euterpe oleracea Mart.) in the diet of Koi carp ( Cyprinus carpio )

The objective of this study was to evaluate the effect of dietary supplementation with Citrus sinensis (L.) Osbeck essential oil on the growth, immune system, and resistance to Aeromonas hydrophila infection in Colossoma macropomum fingerlings. The experiment was conducted with five treatments (control diet, Tween80 diet, and diets supplemented with 200, 400, and 800 mg L⁻¹ of C. sinensis essential oil) with four replicates. At the end of the experimental period, growth parameters were measured, and blood samples were collected for thrombogram, leukogram, and phagocytic activity analysis. A bacterial challenge with A. hydrophila was conducted for 96 h. C. macropomum fingerlings that were fed with 400 and 800 mg L⁻¹ of C. sinensis essential oil had the highest growth parameters, with final weights of 533.18 ± 2.03 mg and 531.91 ± 2.67 mg, respectively, and an increase in the number of thrombocytes, lymphocytes, monocytes, and neutrophils, as well as higher phagocytosis rates compared to the control group. Regarding the challenge, fish in the 400 and 800 mg L⁻¹ treatments also exhibited the lowest cumulative mortality rate (26.66% ± 3.33%). Therefore, supplementation with C. sinensis essential oil promotes growth, improves health, and enhances resistance to A. hydrophila in C. macropomum fingerlings.

This study aimed to perform in vitro antiparasitic and antimicrobial tests with the essential oil (EO) ofSchinus terebinthifoliusagainst of fish and shrimp. The chemical composition of the EO ofS. terebinthifoliuswas determined by gas chromatography. For the antiparasitic test, the protozoanEpistylissp. obtained from parasitizedOreochromis niloticuswas used, and exposed to different concentrations of EO (2%, 1%, 0.5%, 0.25%), and control with 1% grain alcohol. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) test with EO ofS. terebinthifoliusevaluated the antimicrobial potential, with serial dilutions starting at 2% and control with 1% grain alcohol, using the strains ofAeromonas hydrophila(2.2 × 10⁸ CFU mL⁻¹),Edwardsiella tarda,Vibrio parahaemolyticus,V. harveyi, andV. alginolyticus(2.0 × 10⁸ CFU mL⁻¹). Chemical analysis revealed that the major EO compounds ofS. terebinthifoliuswere δ‐3‐Carene (56.00%) and α‐Pinene (16.89%). In the antiparasitic test, the concentration of 2% EO showed 100% efficacy againstEpistylissp. within 5 min. In the antimicrobial tests, the concentration of 2% EO was effective against all bacteria tested. The EO ofS. terebinthifoliusdemonstrated antiparasitic and antimicrobial activity at a concentration of 2%, standing out as an alternative to conventional antibiotics.