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Fruit residues represent alternative ingredients that can be included in diets of tambaqui, Colossoma macropomum. This study evaluated the growth performance of tambaqui fed diets containing different levels of guava agroindustrial residue. The experiment was based on a completely randomised design, with 105 fish randomly distributed in 15 plastic 60 L-1 boxes with a water recirculation system. Feeding was carried out to apparent satiety for 45 days, using diets with 0, 50, 100, 150 and 200 g kg-1 inclusion of guava residue. Biometrics were performed every 15 days. Quadratic effect (p < 0.05) was observed for daily feed intake and apparent feed conversion, with optimum levels of 4.86 and 6.05% inclusion of guava residue, respectively. There was no significant difference (p > 0.05) in relation to final weight, weight gain, specific growth rate, hepato-somatic index, survival rate and protein efficiency rate by the dietary treatments. The inclusion of up to 150 g kg-1 of the guava agroindustrial residue in the feed did not compromise the performance of tambaqui juveniles.

The effect of fairy shrimp “branchoneta” as the first exogenous feed for tambaqui postlarvae was evaluated. A hundred and eighty larvae were distributed in 12 aquariums, containing 1.5L of water and the stocking density was 10 larvae per liter. The trials lasted for 20 days and postlarvae were submitted to three diets (T1: Commercial feed, T2: branchoneta, and T3: Commercial feed with branchoneta), with a completely randomized design with four replicates for each treatment. During the trials, the water quality parameters were kept within ideal conditions for the species. The tambaqui postlarvae submitted to T2 and T3 showed better survival rates respectively.  Regarding the postlarval development, larvae fed with only branchoneta had a better final weight (3.48 mg), daily weight gain (0.14 mg day-1), and the best specific growth rate (8.62%). The results also showed that the tambaqui postlarvae fed with only commercial feed developed less efficiently due to lower rates of survival and growth. The present study indicates that the branchoneta promoted greater development and survival rates of the tambaqui postlarvae and therefore, it presents good potential as a live food for the species.

Vitellogenins (Vtg) are glycolipophosphoproteins synthesized by oviparous vertebrates as yolk proteins precursors. These proteins have been studied for their role in reproduction and in endocrine disruption. In this work, we report the first proteomic study towards the characterization of Vtg from Pseudoplatystoma fasciatum, Piaractus brachypomus and Colossoma macropomum. Male specimens of each of the three fish species were estradiol-induced (experimental) and non-induced (control). The initial Vtg characterization was made by 2D protein gel electrophoresis of both groups The identification of the high molecular weight spots, presumed to be Vtgs, was assessed by MALDI-TOF mass spectrometry analysis. A post-translational modification study was performed by differential staining of 2D gels in order to visualize phosphoproteins and glycoproteins. Plasma samples from the three species, induced with estrogen, showed three high molecular weight spots with variable isoelectric points. Post-translational modifications showed that Vtgs from P. brachypomus and C. macropomum presented a phosphorylated and glycosylated subunit, while the same subunit in P. fasciatum was only glycosylated. This characterization will help in the development of reliable immunoassays, which could be used for studies of endocrine disruption or for the improvement of artificial spawning, by uncovering the time of fish maturation or sex determination.

The present work evaluated physiological stress responses of tambaqui to transport and their consequences to rigor mortis of fish slaughtered by hypothermia or by carbon dioxide asphyxia. Fishes were submitted to experimental transport to evaluate four fish stress stages before slaughter: post-harvest, after transport, after 24 h and 48 h recoveries. Fish stress after transport was the most acute, and fish slaughtered after that by hypothermia had the quickest rigor mortis onset: 60 min, while fish slaughtered by asphyxia had rigor mortis onset in 120 min. Fish slaughtered just after harvest had rigor mortis onset in 135 min for both slaughter methods (hypothermia or asphyxia). Fishes recovered from transport stress had slower rigor mortis onset: 225 min and 255 min after 24 h and 48 h recovery, respectively, for both slaughter method. No influence from slaughter method was observed on rigor mortis resolution in all the fish. Rigor mortis of fish slaughtered after transport ended in 12 days. Rigor mortis of fish slaughtered after harvest ended in 16 days. Fish recovered from transport stress had rigor mortis end at 20 days and 24 days after 24h and 48h recovery, respectively. Slaughter of tambaqui for industry is rather recommended after stress recovery, in order to extend the rigor mortis period.

The Clibadium spp. is a shrub of occurrence in the Amazon, popularly known as Cunambi. The compounds in the leaves demonstrate ichthyotoxic properties, and its major substance, cunaniol, is a powerful central nervous system stimulant with proconvulsant activity. Few current studies relate behavioral changes to the electrophysiological profile of fish poisoning. This study aimed to describe the behavioral, electromyographic, electroencephalographic, electrocardiographic, and seizure control characteristics of anticonvulsant drugs in Colossoma macropomum submitted to cunaniol intoxication during bathing containing 0.3 μg/L cunaniol. The behavioral test showed rapid evolution presenting excitability and spasms, which were confirmed by the analysis of Electroencephalogram (EEG), Electromyogram (EMG), and changes in cardiac function detected in the ECG. Cunaniol-induced excitability control was evaluated using three anticonvulsant agents: Phenytoin, Phenobarbital, and Diazepam. While phenytoin was not effective in seizure control, diazepam proved to be the most efficient. These results demonstrate the susceptibility of Colossoma macropomum to cunaniol poisoning, given that the central nervous system and electrocardiographic changes were considered severe.

In recent years, the use of natural products as alternatives to synthetic anesthetic agents has gained notoriety in aquaculture. Among the essential oils studied, Lippia alba has attracted attention due to its diverse pharmacological properties, including sedative and anesthetic effects. This study aims to evaluate the anesthetic activity of Lippia alba essential oil (LAEO) to propose a therapeutic window for its use in tambaqui ( C . macropomum ). In this research, juvenile tambaqui (10.9 ± 5.9g, n = 90) were submitted to anesthetic baths with LAEO at concentrations of 80–140 μL.L -1 for behavioral assessment and electrophysiological recordings. The findings showed that all concentrations were effective in inducing the loss of posture reflex and its subsequent reversible return. However, electrocardiographic recordings at concentrations of 120 and 140 μL.L -1 revealed alterations in the graph elements, indicating more intense bradycardia and atrioventricular block during anesthetic induction. Nevertheless, during the anesthetic recovery period, cardiac normality was restored at all tested concentrations, although more slowly at the highest concentration (140 μL.L -1 ). Thus, we conclude that this oil is safe for providing short-term anesthesia at concentrations between 80 and 100 μL.L -1 in C . macropomum specimens.

Frugivory and seed dispersal by fish is an important mutualistic interaction in complex and species-rich tropical rivers. The local ecological knowledge (LEK) held by fishers can provide new information on relationships between fishes and plants in less studied rivers. This study aims to investigate the feeding interactions between frugivorous fish and plants through interaction networks based on the fishers' LEK in three rivers in the Brazilian Amazon (Negro, Tapajós and Tocantins). A total of 418 fishers were interviewed in 24 communities (eight in each river). The studied fishes were tambaqui (Colossoma macropomum), matrinxã (Brycon spp.), pacu (Myloplus spp.), pacu manteiga (Mylossoma duriventre), pirapitinga (Piaractus brachypomus), and jaraqui (Semaprochilodus spp.). The interviewed fishers cited a total of 92 plants consumed by the six frugivorous fishes in the three rivers. The interaction networks showed a higher nestedness in the Tocantins, greater connectance and modularity in the Tapajós and more specialization in the Negro, where the protected areas may have contributed to a more complex and specialized interaction network. The more nested network in the Tocantins River indicated the loss of specialized interactions in disturbed communities. The Tapajós River network showed the highest number of interactions between fish and plants, but this river has been threatened by environmental changes. Fishers' LEK associated to network analyses can advance our understanding on ecological interactions. This approach can be also useful to evaluate and mitigate ecological effects from anthropic changes in the Amazon and other high diverse tropical rivers.

Tilapia and catfish are the most popular fish species in aquaponics. However, they are not well-accepted in all markets, and finding alternative species is important in order to increase the variety of food products and meet market demands. South America has several potential fish species for aquaponics systems. Encouraging the implementation of integrated aquaculture systems by providing information about the production of South American species can help to increase the supply of high-quality food and aquaculture diversification. Thus, data for five South American fish species with potential for aquaponics were compared with existing data for the main traditional warm water species in this system, tilapia and catfish. Moreover, the degree of suitability of the novel species for these systems in terms of zootechnical performance, tolerance to water quality and nutritional composition of fish flesh were discussed. The South American species considered were jundia or silver catfish (Rhamdia quelen), yellowtail lambari (Astyanax lacustris), pacu (Piaractus mesopotamicus), tambaqui (Colossoma macropomum) and snook (Centropomus spp.). Their description and the tabular comparison with the most traditional aquaponic-cultured species show they are suited for this production system. How suitable they are will depend on the system design, as well as the regional characteristics of the market where they will be produced.

Scarce genomic resources have limited the development of breeding programs for serrasalmid fish Colossoma macropomum (tambaqui) and Piaractus mesopotamicus (pacu), the key native freshwater fish species produced in South America. The main objectives of this study were to design a dense SNP array for this fish group and to validate its performance on farmed populations from several locations in South America. Using multiple approaches based on different populations of tambaqui and pacu, a final list of 29,575 and 29,612 putative SNPs was selected, respectively, to print an Axiom AFFYMETRIX (THERMOFISHER) SerraSNP array. After validation, 74.17% (n = 21,963) and 71.25% (n = 21,072) of SNPs were classified as polymorphic variants in pacu and tambaqui, respectively. Most of the SNPs segregated within each population ranging from 14,199 to 19,856 in pacu; and from 15,075 to 20,380 in tambaqui. Our results indicate high levels of genetic diversity and clustered samples according to their hatchery origin. The developed SerraSNP array represents a valuable genomic tool approaching in-depth genetic studies for these species.

Dichlorvos is an acutely toxic organophosphorous pesticide that is known as a classical acetylcholinesterase (AChE; EC 3.1.1.7) inhibitor. Here, the brain AChE from the important Amazonian fish tambaqui (Colossoma macropomum) was assayed in the presence of this insecticide and also of deltamethrin, a classical sodium and potassium channel inhibitor (negative control). Four tissue homogenates were analyzed in triplicate for AChE activity using acetylthiocholine as the substrate and 5,5'-dithiobis(2-nitrobenzoic) acid (DTNB) as the color-developing agent. Each tissue homogenate represented pooled brains from five fish. The inhibitory effect of dichlorvos on AChE activities was determined at concentrations from 0.001 to 10 ppm and compared to controls. This effect followed an exponential decay model (y = 9.420 + 26.192e(-x/5.380); r2 = 0.989), presenting IC50 (the concentration of dichlorvos that is required for 50% of AChE inhibition) of 0.081 ppm (0.368 umol/L). No effect was observed for the deltamethrin, and the concentration 0.0452 umol/L of dichlorvos was significantly different from this control. These results suggest that tambaqui brain AChE can be proposed as a biomarker for dichlorvos and can be used as a tool for aquatic environment monitoring.