Tambaqui Colossoma Macropomum Research Articles

Ovicidal effect of essential oils of Lippia alba, Lippia sidoides and Lippia gracilis on the acanthocephalan Neoechinorhynchus buttnerae (Eoacanthocephala: Neoechinorhynchidae).

Acanthocephalosis in tambaqui Colossoma macropomum culture is a limiting factor for the production of the species, being the most recurrent, which makes it necessary to develop strategies to control parasitosis even in the early stages of parasite development. This study aimed to elucidate the morphological characteristics of eggs of the acanthocephalan Neoechinorhynchus buttnerae and the ovicidal effect of the essential oils of Lippia alba, Lippia sidoides, and Lippia gracilis. The parasites were collected from hosts naturally infected with N.buttnerae, and the eggs obtained from the female 'parasites' abdominal cavity were added to 12-well plates containing the essential oils at different dilutions. After the eggs (N=300) were separated and measured (length and width) with the aid of an optical microscope coupled to a digital program, the viability of the treated eggs was monitored 24h after treatments, L.gracilis essential oil was 100% effective at the highest concentration, whereas L.sidoides essential oil showed over 50% efficacy at 2mg/ml, reaching 100% efficacy at all higher concentrations. Lippia. alba essential oil did not show satisfactory efficacy in preventing N.buttnerae egg hatching.

Zootechnical indices and digestibility in juveniles of tambaqui Colossoma macropomum fed a diet containing particulate maize.

Three experiments were done with different particle sizes of corn feed on its zootechnical performance, passing rate and apparent digestibility of juvenile tambaqui (Colossoma macropomum). In the first, 200 juveniles were used and distributed in 20 tanks (220 L), 10 fish per unit (four replicates). The experimental system used to record passage time was composed of five incubators with 200 L. In the second, 75 juveniles were used per 55 days (three replications). In the third, 75 juveniles were used and distributed in five incubators of 200 L. All experiments were performed randomly. Different linear behavior treatments were observed for apparent digestibility of crude protein; and the smaller particle size (150 μm) had better results digestibility. smaller particle size of the corn had better results, affected the growth performance of tambaqui and the apparent digestibility of crude protein and ether extract. Thus, is recommended that a particle size of 150 μm of corn be used for tambaqui.

FREQUÊNCIA ALIMENTAR DE JUVENIS DO TAMBAQUI (Colossoma macropomum) CRIADOS EM SISTEMA DE RECIRCULAÇÃO

Recirculation aquaculture systems require proper food management, and feeding frequency is one of the most important factors to obtain optimal results in production. The tambaqui Colossoma macropomum presents satisfactory zootechnical performance in Pará State, but research related to its food management in recirculation aquaculture systems are scarce, in view of this, this work aimed to evaluate the zootechnical performance of tambaqui juveniles raised in Recirculation aquaculture systems. A total of 324 tambaqui juveniles with an average initial weight of 24.7 g were used in a recirculation system with three treatments in triplicate, with fish fed two, three and four times a day. The fish were fed with commercial ration with 32 and 36% of crude protein for 40 days and with a feeding rate of 4%. During the experiment were measured: temperature; pH; dissolved oxygen; pH; conductivity; turbidity; salinity, dissolved solids and nitrogen compounds of the system water, and these had a low variation between treatments. The fish fed with higher frequencies had higher final average weight and higher specific growth rate, with this, from the results obtained, it is concluded that the best feeding frequency for tambaqui juveniles is three times a day.

A high-density linkage map and sex-linked markers for the Amazon Tambaqui Colossoma macropomum

BackgroundTambaqui (Colossoma macropomum, Cuvier, 1818) is the most economically important native freshwater fish species in Brazil. It can reach a total length of over 1 m and a weight of over 40 kg. The species displays a clear sex dimorphism in growth performance, with females reaching larger sizes at harvest. In aquaculture, the production of monosex populations in selective breeding programmes has been therefore identified as a key priority.ResultsIn the present study, a genetic linkage map was generated by double digest restriction-site associated DNA (ddRAD) sequencing from 248 individuals sampled from two F1 families. The map was constructed using 14,805 informative SNPs and spanned 27 linkage groups. From this, the tambaqui draft genome was improved, by ordering the scaffolds into chromosomes, and sex-linked markers were identified. A total of 235 markers on linkage group 26 showed a significant association with the phenotypic sex, supporting an XX/XY sex determination system in the species. The four most informative sex-linked markers were validated on another 206 sexed individuals, demonstrating an accuracy in predicting sex ranging from 90.0 to 96.7%.ConclusionsThe genetic mapping and novel sex-linked DNA markers identified and validated offer new tools for rapid progeny sexing, thus supporting the development of monosex female production in the industry while also supporting breeding programmes of the species.

Depletion study and estimation of the withdrawal period for albendazole in tambaqui (Colossoma macropomum) parasitised by acanthocephalan (Neoechinorhynchus buttnerae) treated with albendazole-containing feed

ABSTRACT This study provides the first data related to albendazole (ABZ) and its main metabolites [albendazole sulphoxide (ABZSO), albendazole sulphone (ABZSO2), and albendazole-2-amino sulphone (ABZ-2-NH2-SO2)] residue depletion in tambaqui (Colossoma macropomum) parasitised by acanthocephalan (Neoechinorhynchus buttnerae). The ABZ withdrawal period was also calculated. The fish received a daily dose of 10 mg ABZ kg−1 body weight (b.w.) via medicated feed for 34 days. Samples of target tissue (muscle plus skin in natural proportions) were collected 24, 48, 72, 120, 168, 240, and 336 h after the end of ABZ administration. The quantitation of ABZ residues and its metabolites in the target tissue was performed using a validated ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analytical method. After treatment, ABZ in the target tissue was rapidly metabolised over time, and ABZSO was the most persistent metabolite and was shown to be at the highest levels in the target tissue. Considering the maximum residue limit (MRL) established by Codex Alimentarius in the muscle (100 μg kg−1, species not specified), a withdrawal period of 4 days (112 °C-day) was estimated for the total residue (sum of ABZ and its metabolite residues). Considering data reported in the literature and data obtained in this study, it is suggested that the total residue be considered as marker residue to be adopted for fish in the legislative framework.

Lysine effect on the characterization of fillet, by-products, residues, and morphometry of tambaqui Colossoma macropomum (Cuvier, 1818)

This study aimed to evaluate the yields of by-products and residues and the morphometry of juvenile tambaqui Colossoma macropomum undernutrition with different levels of lysine. Diets were elaborated containing 6.60, 9.72, 12.84, 15.96, 19.08, and 22.20 g kg -1 of total lysine, and these were fed to fish distributed in 18 tanks (310 L each one) for 90 days. Morphometric analysis, measurements of whole fish, by-products, and residues were taken and compared to each other. All variables were validated using ANOVA, Tukey's test, and quadratic regression analysis ( P < 0.05). No differences were found for the morphometric variables ( P > 0.05). The ratio between morphometric data for the standard and total length showed significance at levels of 9.72 and 15.96 g kg -1 ( P = 0.03). The gutted fish and fillets, the protein and lipid contents of the fillets, and the weights and lengths of the intestines did not change ( P > 0.05). Moisture was modified with lysine at levels of 22.20 g kg -1 ( P = 0.00), and minerals, between 6.60 and 22.20 g kg -1 ( P = 0.01). The increase in lysine levels in the diet led to an increase in fin weight ( P = 0.00). It was concluded that the addition of lysine in the diet did not directly influence the morphometry and yields of the fish in the juvenile phase, but it did affect the fin waste and the skin by-product.

Growth performance, hematological responses and economic indexes of Colossoma macropomum (Cuvier, 1818) fed graded levels of glycerol

The aim of this study was to evaluate the performance, hematological responses and economic indicators of juvenile tambaqui Colossoma macropomum fed different levels of partial replacement of corn by glycerol (0%, 25%, 50%, 75%, and 100%). The experiment was conducted for 90 days in the production of aquatic organisms lab at the Nilton Lins University, Manaus, Brazil, in a completely randomized design, and consisted of four treatments, four repetitions and two sampling times. In total, 240 juveniles were used with initial average weight and standard length of 15.32 ± 1,61 g and 8.03 ± 0.22 cm, respectively. The fish were maintained in twenty 310 L water tanks that had a closed system with no reuse, continuous aeration, siphoning and replacement of water every 48 h. Feeding was twice a day with the experimental diets, which contained 28% crude protein. The following parameters were considered: zootechnical checks (weight gain + survival %), welfare (health) (hepatosomatic index + condition factor + viscerosomatic index), economic (Economic efficiency rate + economic profitability index) and hematology (hematology + metabolites + ions). The results of the study show that diets for juvenile tambaqui can contain up to 50% replacement of corn by glycerol without compromising the fishes' development under the conditions studied.

Menthol exposure induces reversible cardiac depression and reduces lipid peroxidation in the heart tissue of tambaqui Colossoma macropomum

Exposure to menthol is expected to alleviate physiological and oxidative stress in fish. Yet, its effects as an anesthetic-like compound on the heart function and associated physiological and biochemical changes still need further clarification. This study aimed to analyze the effects of menthol on the cardiac function and oxidative stress responses of Colossoma macropomum exposed to short-term baths. Fish were divided into three groups: control, menthol-exposed fish (40, 60 and 80 mg L−1) and fish in recovery. The electrocardiogram (ECG) tracing patterns, wave intervals (RR; QT), complex duration (QRS) and heart rate were assessed after 5 min recordings throughout exposure and recovery. Total antioxidant capacity against peroxyl radicals (ACAP), glutathione S-transferase (GST) activity and lipoperoxidation (LPO) levels were also evaluated in the heart tissue. All concentrations of menthol depressed the heart rate and prolonged RR and QT intervals in a concentration-dependent fashion. QRS complex duration was only reduced at the highest dose of menthol. During recovery, heart rate and mean amplitude were still reduced at 60 or 80 mg L−1 menthol, whereas wave intervals were still longer at these concentrations. Notwithstanding, QRS complex resumed its normal duration during recovery. GST activity and ACAP were unchanged in fish exposed to menthol. However, LPO reduced in fish exposed to 40 and 60 mg L−1 menthol. In conclusion, all concentrations of menthol induced anesthesia in C. macropomum without causing mortality, albeit provoking transient cardiac alterations. Menthol at 40 and 60 mg L−1 could be considered suitable concentrations to immobilize fish as they not only did not compromise cardiac function but reduced LPO in the heart. Yet, menthol at 80 mg L−1 or higher doses should be avoided as there is a potential for the emergence of a life-threatening cardiac depression and oxidative stress.

ETosis in tambaqui Colossoma macropomum: A programmed cell death pathway and approach of leukocytes immune response

Tambaqui Colossoma macropomum is the most cultivated native fish in South America and Aeromonas hydrophila is one of the main bacteria infecting tropical fish. Despite the economic importance of this round fish, to date, there has been a paucity of investigations into haematological changes in tambaqui. In this study, detailed blood analyses (0 h, 6 h, 24 h, 7 d and 14 d) following intraperitoneal challenge with A. hydrophila were performed. After analysing the results, there was a suspicion of a novel cell death mechanism via extracellular traps (ETosis) in tambaqui. The search for ETosis was based on differential interference contrast (DIC) microscopy and scanning electron microscopy (SEM) assays through application of an adapted protocol applying co-incubation of leukocytes with A. hydrophila. The cells were investigated at: 0 h (control), 4 h and 7 h after incubation. The complete haemogram profile showed an uncommon severe leukopenia in early phases of infection (6 h, p < 0.001 and ≤ 0.05), due to significant decreases in the three main leukocytes: lymphocytes (6 h, p ≤ 0.001), monocytes (6 h, p ≤ 0.05) and neutrophils (6 h and 24 h, p ≤ 0.01 and p ≤ 0.05). Leucocytosis and lymphocytosis (p ≤ 0.01) were ascertained only 7 days post-infection. Through DIC and SEM, we discovered that leukocyte suicide exposed the nuclear contents between 4 and 7 h after stimuli with bacteria. The leukogram profile associated with DIC and SEM analyses suggested that tambaqui leukocytes underwent a programmed death (ETosis) in order to expose chromatin and granule proteins as a trap to bind and then kill bacteria; thus, preventing A. hydrophila from spreading and resulting in leukopenia during the early phase of bacterial infection. In this paper, we presume that ETosis is one of the last resources for tambaqui to contain the infection, and after this leukocyte strategy, a high number of phagocytic cells are produced and released into the peripheral circulation.

Genetic variability in Tambaqui generations of the breeding program in the Central-West Region of Brazil

The implementation of fish breeding programs in Brazil has brought significant results in the productivity of tilapia. However, the insertion of native species with great potential (such as Tambaqui Colossoma macropomum) in these programs is still recent, and thus requires genetic information for monitoring and enabling their consolidation into the programs. The objective of the present study was to evaluate the genetic diversity of the parental generation (G0) and two consecutive generations (G1 and G2) in the C. macropomum genetic improvement program, located in the municipality of Sorriso, Mato Grosso, Brazil. Ninety caudal fin samples were collected (30 samples per generation) for DNA extraction. The genetic study implemented seven microsatellite markers (Cm1A8, Cm1A11, Cm1D1, Cm1E3, Cm1F4, Cm1F5, and Cm1H8). A total of 17 alleles were amplified, with variations in the mean number between four to two alleles per locus. The size per locus ranged from 170 to 360 bp. The average inbreeding coefficient was 0.126 (G0), -0.040 (G1), and 0.131 (G2). No null or exclusive alleles were found. The observed heterozygosity values for G1 and G2 demonstrated the preservation of genetic variability (0.453 and 0.409, respectively). In conclusion, the genetic diversity of the parental generation (G0) and the two progenies generations (G1 and G2) were adequate, which demonstrates that the genetic improvement program was conducted correctly; however, it is important to continue to evaluations the genetic diversity of the future progeny.

Histopathological alterations caused by monogenean parasites the gills of tambaqui Colossoma macropomum (Serrasalmidae)

Monogeneans are ectoparasites of fish with a global distribution. In farmed fish, high infestations may result in morbidity and mortality. This study investigated the histopathological effects of three species of monogeneans Anacanthorus spathulatus, Notozothecium janauachensis and Mymarothecium boegeri on the gills of farmed Colossoma macropomum. Parasitological indices revealed a prevalence of 100%, and a mean abundance of 81.3 ± 11.8. This infection caused displacement of the gill epithelium, focal hyperplasia of epithelial cells, lamellar fusion, congestion and shortening of the secondary lamellae of gills, in addition a complete fusion of the secondary lamellae. However, these tissue alterations were reversible and punctually located lesions, which may not compromise the normal functioning of gills. Lastly, this study showed the potential damages caused by parasite monogeneans to gills of infested fish, thus sanitary management is essential for the growth of fish farm of C. macropomum.

Chemical composition of commercial tambaqui (Colossoma macropomum) cuts in different body weight classes (Amazon: Brazil)

It is important to know the nutritional composition of the fish, especially the nutritional value of the commercial cuts most consumed by the population. The aimed of this study was to evaluate the chemical composition of commercial tambaqui (Colossoma macropomum) cuts in different classes of body weight. The sample collections were carried out in processing units in two municipalities in the state of Rondônia, Brazil. The Data on 200 fish were recorded, with weight ranging from 1000 to 4700 g. Five classes of body weight were established, class 1 - below 1.2 kg; class 2 - from 1.21 to 1.8 kg; class 3 - from 1.81 to 2.4 kg; class 4 - from 2.41 to 3.5 kg; class 5 - over 3.5kg. The commercial cuts were lyophilized and intended for chemical analysis. The Kruskal-Wallis test (α=0.05) was used to compare the averages. The composition of commercial cuts was different in weight classes (p&lt;0.05). The filet presented more representative values in mineral matter, crude protein and total lipids and lower humidity for class 4 (from 2.41 to 3.5 kg). The classes 1 and 5 (below 1.2 and over 3.5 kg) were different (p&lt;0.05) in relation to the lipid and moisture content in the commercial filet and rib cuts. The tambaqui steak in class 4 have a higher lipid content compared to the average of the lightest body weight classes, 9.99 vs 4.50%, in addition to having a lower moisture content (p&lt;0.05). The tambaqui band was different (p&lt;0.05) in relation to nutritional components between body weight classes, with class 4 being richer in minerals, crude protein and lipids in dry matter. Therefore, the class 4 was the most efficient (p&lt;0.05) for production and commercialization. Because the tambaquis with body weight between 2.4 to 3.5 kg stood out in relation to the nutritional components in the different commercial cuts.

Protein profile as a quality indicator of cryopreserved semen from Tambaqui Colossoma macropomum (Cuvier, 1818).

The aim of this study was to evaluate the association between proteins in the seminal plasma of tambaqui Colossoma macropomum (Cuvier, 1818) with seminal quality indicators after thawing. The semen was cryopreserved with a dilution based on BTS with 8% DMSO. A 200 µL sample of semen from each animal was diluted in 800 µL BTS, centrifuged at 800 rpm, and the supernatant was cryopreserved to further analyze of the protein profile of seminal plasma through one-dimensional electrophoresis (SDS-PAGE). After 15 days of cryopreservation, a cryopreserved semen straw was thawed to analyze both qualitative and quantitative parameters. When considering all collections, the SDS-PAGE identified 15 protein bands in the seminal plasma of tambaqui. When the interaction (presence or absence) between proteins observed in the seminal plasma and the post thawed spermatic parameters was evaluated, we observed a great influence of the presence of proteins on spermatic quality. A greater (P<0.05) fertilization rate was observed with the presence of proteins 12, 34, 44, 85, and 90 kDa. Proteins in seminal plasma of tambaqui influenced the spermatic quality after thawing, and thus, they can be utilized as an indicator of sperm quality, especially the proteins with a molecular weight ≤ 50 kDa.

Patterns of the innate immune response in tambaqui Colossoma macropomum: Modulation of gene expression in haemorrhagic septicaemia caused by Aeromonas hydrophila

The production of tambaqui Colossoma macropomum has recently reached a milestone, being considered the main native species produced in South American continental waters. Despite the importance of this fish, its immunity is not well understood. In this study we established some patterns of innate immunity for the species via two experiments. Both studies evaluated the fish in the absence (intraperitoneal saline) or presence (intraperitoneal, 3 x 107 CFU/mL of Aeromonas hydrophila at 0.1 mL/10 g of living weight) of infection at 5 points over time-course of 14 days (0 h, 6 h, 24 h, 7 d, 14 d). In the first experiment, the partial gene sequences and gene expression of IL-1β, IRAK-1, C3, C4, lysozyme, IL-10, HSP70 and β-actin were determined in the main secondary lymphoid organs of fish: the spleen and head kidney. The second study was performed to analyse the alternative complement pathway ACH50 in serum to support the elucidation of C3 gene expression. Results of the gene expression assays showed a tendency towards up-regulation of immune genes in infected fish in early phases of infection (mostly around 6 h and 24 h) and in the chronic phase (7 d and 14 d), with the exception of HSP70 which showed a down-regulation in infected fish. Our results also suggested that lysozyme was evolved in both pro- and anti-inflammatory activities. For genes of the complement system, it was demonstrated that C4 regulation followed the tendency of pro-inflammatory genes. However, the C3 gene was, surprisingly, not expressed in most fish and this corroborated with the results of the complement system activity in serum that also did not show activity in most fish. The possible reasons for the regulation of gene expression and association with fish disease are addressed in this paper.

Ocimum basilicum essential oil as an anesthetic for tambaqui Colossoma macropomum: Hematological, biochemical, non-specific immune parameters and energy metabolism

The present study evaluated the efficacy of Ocimum basilicum (basil) essential oil in the anesthetic induction and recovery of juvenile tambaqui Colossoma macropomum and verified its physiometabolic effects after biometric handling. Juveniles (86.51 ± 7.82 g) were exposed to different concentrations of basil essential oil: 400, 500, 600, 700, 800, 900, and 1000 μL L−1. Subsequently, the fish were divided into five groups: control (non-handled fish), handling without anesthetic (water only), handling with ethanol (720 μL L−1), and handling with Ocimum basilicum essential oil (400 and 800 μL L−1). The shortest (p < 0.05) time to induce anesthesia was at a concentration of 1000 μL L−1 (222 s). The recovery time from anesthesia did not differ significantly among different concentrations (400–1000 μL L−1). The results of the present study confirm the essential oil of O. basilicum as a new and safe natural anesthetic for juvenile tambaqui. The use of this essential oil in biometrics handling procedures reduces or attenuates the secondary responses to handling stress without showing deleterious effects on the non-specific immune system or metabolism of energy, carbohydrates, and lipids. However, further studies are necessary to determine the exact mechanism of action of this essential oil.

Motile Aeromonas septicemia in tambaqui Colossoma macropomum: Pathogenicity, lethality and new insights for control and disinfection in aquaculture

Tambaqui Colossoma macropomum is the most produced native fish in South America. Besides the lack of knowledge regarding bacteria-stricken diseases, the unappropriated using of off-label therapies are common. In this study, Aeromonas hydrophila pathogenicity for tambaqui was first established by Koch's Postulate. Lethal doses (LD) were settled for investigation of clinical signs and mortality. The antimicrobial activities were investigated by disk-diffusion test against 11 antibiotics and by broth microdilution methods against 3 antibiotics, 7 disinfectants and 11 herbal medicines. LD experiment showed up to 80% of fish mortality, skin darkness, ulcers, hemorrhage, lethargy and hypo/anorexia in all groups, with exception of control. The LD10,50,90 and 99 were established in 4.1 × 107, 8.8 × 107, 1.9 × 108 e 3.6 × 108 CFU/mL, respectively. Ceftriaxone, florfenicol, oxytetracycline and thiamphenicol were considered promising against A. hydrophila. All herbal medicines were classified as bactericides, but clove Eugenia caryophyllata and cinnamon Cinnamomum zeylanicum displayed strongest activities. Among disinfectants, malachite green was the only that did not present acceptable values, discouraging its use. In conclusion, Koch's postulate was fulfilled and tambaqui entered to the vast list of A. hydrophila hosts and promising results of chemical substances were provided, contributing to motile Aeromonas septicemia (MAS) control.

Custo de produção e rentabilidade da criação de tambaqui Colossoma macropomum no estado do Pará, Amazônia, Brasil

O tambaqui Colossoma macropomum é a espécie nativa mais importante da piscicultura brasileira, sendo produzida especialmente na região amazônica. No estado do Pará, a criação comercial ocorre principalmente em viveiros escavados e em tanques-rede ou gaiolas flutuantes. O objetivo deste estudo foi analisar o custo de produção e a rentabilidade da criação de tambaqui no estado do Pará. Adotou-se a estrutura de custo operacional e indicadores de eficiência econômica para avaliar uma piscicultura com 12 viveiros escavados de 1.200 m2 cada, no município de Irituia/PA, e a criação de peixes em 12 gaiolas flutuantes de 4 m3 de volume útil, em Juruti/PA. Em novembro de 2015, o custo de implantação da piscicultura em viveiros escavados foi estimado em R$ 110.357,76 e o custo operacional efetivo em R$ 79.661,92. A receita bruta foi de R$ 108.000,00, o lucro operacional mensal de R$ 1.984,11, a taxa interna de retorno de 25%, o valor presente líquido de R$ 72.914,16 e o período de retorno do capital de 4,91 anos. Em dezembro de 2015, o custo de implantação da piscicultura em gaiolas flutuantes foi estimado em R$ 24.576,72 e o custo operacional efetivo em R$ 20.158,35. A receita bruta foi de R$ 27.000,00, o lucro operacional mensal de R$ 380,13, a taxa interna de retorno de 25%, o valor presente líquido de R$ 10.133,88 e o período de retorno do capital de 3,58 anos. As pisciculturas mostraram-se investimentos rentáveis, com capacidade de maximização do lucro, caso sejam adotadas estratégias produtivas mais adequadas.

Copaifera oleoresins as a novel natural product against acanthocephalan in aquaculture: Insights in the mode of action and toxicity

Tambaqui Colossoma macropomum is the main South American fish in continental aquaculture. However, its production has been hampered by acanthocephalan Neoechinorhynchus buttnerae. In this study, we evaluated the antiparasitic potential of five oleoresins (ORs): Copaifera duckei, Copaifera pubiflora, Copaifera reticulata, Copaifera paupera and Copaifera multijuga, as a novel treatment against N. buttnerae, describing their mode of action by histology of the parasite and their toxicity to the host. In in vitro assays, parasites were exposed to three concentrations (0.0467, 0.0934 and 0.1868 mg/ml) of ORs. At the lowest concentration tested (0.0467 mg/ml), none of the ORs had a significant effect on acanthocephalans (p > .05). At the intermediate concentration (0.0934 mg/ml), C. duckei, C. pubiflora and C. reticulata were significantly (p < .05) more effective than C. paupera and C. multijuga. At the highest concentration (0.1868 mg/ml), all species of Copaifera resulted in 100% mortality of the parasites after 24 hr, except C. multijuga. Acanthocephalans killed by the ORs showed generalized vacuolization in the tissues with abnormal accumulation of fluid (remarkable body swelling). We were able to relate the antiparasitic effect of ORs to their composition (ORs with highest concentration of diterpenes were most effective). In toxicity testing, tambaqui were exposed to the three most effective ORs (C. duckei, C. pubiflora and C. reticulata). All were classified as moderately toxic. In vitro and in vivo tests showed that Amazon ORs have the potential to be included in a list of products for therapeutic purposes in aquaculture.

Feed restriction as a feeding management strategy in Colossoma macropomum juveniles under recirculating aquaculture system (RAS)

This study aimed to evaluate performance, biochemical, hematological and tissue parameters in tambaqui Colossoma macropomum juveniles with initial average weight of 18.0 ± 4.0 g submitted to feed restriction. Three feeding protocols were tested for 56 days: continuous feeding (control); feeding for six days and feed restriction for one day a week (F6R1); and feeding for five days and restriction for two days a week (F5R2). Growth performance was evaluated as weight (W), feed intake (FI), feed conversion ratio (FCR), specific growth rate (SGR) and protein efficiency ratio (PER) at 28 days and from 29 to 56 days of experiment. Blood samples were collected at 28 days (after restriction period in F5R2 and F6R1) and before (at 54 days) and after feed restriction period (at 56 days) to determine hematocrit, hemoglobin, plasma glucose, triglycerides, cholesterol and protein levels. Liver and muscle lipid concentrations, the hepatosomatic index and the mesenteric fat index were evaluated after 28 and 56 days. After 28 days there was a decrease in W, FI and SGR and a better FCR for F5R2, when compared to the control. From day 29 to day 56 there was a decrease in W, FI and a better FCR for F5R2, when compared to the control, while SGR and PER of restricted groups were similar to the control. After 28 days there was a decrease in hematocrit and triglycerides for F5R2, while there was no significant difference in hemoglobin, glucose, cholesterol and protein. Hematocrit was significantly lower in F5R2 group, while there was no treatment, period (54 and 56 days) and interaction between them for hemoglobin concentrations. For glucose, there was an effect of the treatment, as well as an effect of the period but there was no interaction between them. For triglycerides levels there was an effect of treatment, period and interaction between them. Protein and cholesterol levels were influenced only by period and both variables showed an increase in their levels at 56 days, compared to 54 days. After 28 days there was no significant difference for liver lipid levels, muscle lipid and the mesenteric fat index in all treatments; however, there was a decrease in the hepatosomatic index in F5R2. After 56 days there was a decrease in liver lipid levels and the hepatosomatic index with the increase in the restriction period, but there was no significant difference for muscle lipid levels and the mesenteric fat index. Juveniles of C. macropomum submitted to feed restriction for one day a week (F6R1), maintained their body reserves and hematological and biochemistry variables (except for triglycerides at 56 days) unchanged and showed good performance, similar to animals continuously fed for 56 days. However, due to the great heterogeneity of the animals, obtained mainly at the end of the experimental period (56 days), it is recommended to carry out periodic weight classifications for the production of this species in RAS.

The influence of the water pH on the sex ratio of tambaqui colossoma macropomum (CUVIER, 1818)

Tambaqui Colossoma macropomum (CUVIER 1818) is a large Amazonian characid highly appreciated for its meat and therefore over explored by the fishing activity. For the last decades, tambaqui has been the first native fish produced by the Brazilian aquaculture industry. The Amazon Basin is characterized by the presence of acidic and basic waters with pH ranging from 4 to 7.2. In the wild, tambaqui migrates from alkaline white waters where it spawns, to regions of black and acidic water during the rainy season. During this migration, tambaqui swim through waters with different hydrogen potentials that could easily have some effect on its sexual determination process, which has not yet been identified. Hence, the present study aimed at unveiling the possible effect of a peculiar Amazonian environmental feature, pH, on the sex determination of tambaqui. For this, tambaqui larvae at 12 days (post hatch) were kept at pH 6.7, 7.5 (control) and 8.2 for 45 days (until they reached 4 cm of standard length), and then transferred to ponds to grow for sex identification by histology. Although the group treated with more acidic water showed a slight bias towards males, there was no significant difference in both treatments compared to the control group. Therefore, we concluded that the water pH does not influence the sex determination mechanism on C. macropomum.