Tambaqui Colossoma Macropomum Research Articles

Implications of eucalyptol anaesthesia on juvenile tambaqui Colossoma macropomum: Examining behavioural, muscular, cardiac, and haematological responses

This study aimed to evaluate the anaesthetic efficacy and safety of eucalyptol (ECL) in promoting full body immobilisation (anaesthesia), muscle relaxation, and cardiac activity in juvenile tambaqui, C. macropomum. Fish with an average weight of 30.8 ± 4.3 g and a length of 11.9 ± 0.7 cm were used. Initially, specimens underwent anaesthetic baths at ECL concentrations of 300, 400, 500, 600, 700, and 800 μL.L−1 for behavioural assessment. Thereafter, concentrations of 600, 700, and 800 μL.L−1 were arbitrarily selected for further testing, including electrophysiological recordings (EMG and ECG) over 300 s. Additionally, blood samples were collected before and after anaesthesia at 700 μL.L−1 ECL to analyse haematological responses. A total of 10 juveniles were used in each test and recording, divided into three groups: a) control (baseline recording), b) fish exposed only to the vehicle (water mixed with ethanol), and c) fish subjected to ECL for induction and subsequent recovery. The results indicated that higher concentrations of ECL more effectively promoted full body immobilisation (full anaesthesia). The electromyogram revealed significant decreases in muscle contraction power during anaesthetic induction at the three tested concentrations, indicating pronounced muscle relaxation. The electrocardiogram demonstrated a significant reduction in heart rate in fish induced with 700 μL.L−1 (41 ± 4 BPM) and 800 μL.L−1 ECL (35 ± 5 BPM), and the traces from exposure to ECL (600, 700, and 800 μL.L−1 ECL) showed slight, albeit reversible, arrhythmia, which preceded a bradycardic state. All animals gradually returned to sinus rhythm within the appropriate time threshold, suggesting a safe condition for recovery at all concentrations. Haematological results showed that only glucose levels (146.625 ± 30.95 mg.dL−1) were significantly altered compared to the control (76 ± 19.94 mg.dL−1) and ethanol (97.5 ± 16.15 mg.dL−1) groups, with homeostasis resuming after manipulation. In conclusion, ECL was effective in promoting anaesthesia, leading to complete body immobilisation of C. macropomum at concentrations ranging from 300 to 800 μL.L−1 with appropriate induction and recovery times. Concentrations of 600 to 800 μL.L−1 induced pronounced muscle relaxation and cardiac depression without posing a life-threatening scenario. ECL can act safely and reversibly as an anaesthetic agent for use in non-invasive procedures in tambaqui and potentially in other teleost species.

Physiological responses of tambaqui (Colossoma macropomum) fed diets supplemented with silage from fish and vegetables residues.

The demand for products to replace high-cost raw materials, such oil and fish meal, in the manufacture of feed for use in aquaculture, while also guaranteeing the nutritional quality of the diets, is increasing. Silage produced with fish and vegetables residues is a low-cost and efficient protein source. The objective of the present study was to evaluate the physiological and biochemical responses of tambaqui fingerlings fed four different levels of silage included in commercial feed with 28% crude protein, over two periods: 45 and 90 days. Each treatment was carried out over three replications, with 10 tambaqui in each 100 L experimental tank. At the end of each established period, blood samples were collected from five animals from each repetition to determine the hematological and biochemical variables. Body weight and total length, hepatosomatic and liposomal indices and hematocrit of specimens fed with diets supplemented with silage did not exhibit significant changes in both assessment period. After 45 days of feeding, the hemoglobin concentration increased when tambaqui were fed a diet including 20% silage. The red blood cell count, mean corpuscular volume and mean corpuscular hemoglobin did not change between treatments in either period. The total protein concentrations increased significantly in the plasma of tambaqui fed with diets with the inclusion of 5 and 10% of silage, evaluated after feeding for 45 days. It was found that the groups which had silage included in their diet did not exhibit significant alterations in the evaluated parameters, and the diet was therefore not consider harmful to the health of tambaqui. Therefore, the use of silage as a feed supplement during tambaqui farming is a sustainable alternative for producers, as it leads to a reduction of impacts of fish and vegetables waste disposal.

Perfil hemato-bioquímico do tambaqui (Colossoma macropomum Cuvier, 1816) comparando diferentes fases de crescimento em cultivo aquapônico

Abstract The aim of this study was to evaluate the haemato-biochemical parameters of tambaqui Colossoma macropomum in different growth phases in an integrated culture with açai Euterpe oleracea. For this, 240 juvenile tambaqui with initial average weight and length of 21.8 ± 7.74 g and 11.28 ± 6.88 cm were cultured in an aquaponic system integrated with açai for 180 days. During the period, 108 healthy tambaquis were sampled and categorized into five distinct growth phases. At each growth phase blood aliquots were collected. The first phase being fish with an average weight of 103.1 ± 5.27 g; second phase with 823.4 ± 42.6 g; third phase with 1087.75 ± 16.38 g; fourth phase with 1402.0 ± 76.6 g and fifth phase with 1815.0±65.1 g. Water quality variables remained within acceptable parameters for both cultures. Erythrocyte was significantly lower in the first and second phase. Haemoglobin was significantly lower in fish in the first phase. Haematocrit remained the same from the second phase onwards. MCV was significantly lower in fish with 1815.0 ± 65.1 g. Plasma glucose levels were significantly lower in the first and second phases. Cholesterol, triglycerides, and total proteins were significantly higher in fish of the fifth phase. AST was significantly lower in fish from the third phase when compared to fish from the first and fifth phases. ALT was significantly higher in fish from the first phase when compared to fish from the third, fourth, and fifth phases. The results are important tools for assessing the health and well-being of tambaqui in future research involving aquaponic cultures.

Blood cell alterations in Colossoma macropomum juveniles caused by silver nanoparticles.

This study evaluated the median lethal concentration of silver nanoparticles and their effects in fish tambaqui Colossoma macropomum. Therefore, an acute toxicity assay was carried out in completely randomized design evaluating six different concentrations of silver nanoparticles on blood parameters of tambaqui. The silver nanoparticles were produced by chemical reduction with polyvinyl alcohol (AgNP-PVA). The lethal concentration 50% (LC50) was estimated using probit regression. The blood was collected, analyzed and the data were submitted to T-test (dying x surviving fish) and Tukey test (surviving fish). An increase in glucose, hematocrit, total plasma protein, hemoglobin, erythrocytes, leukocytes, monocytes, and neutrophils as well as reduced MCV (mean corpuscular volume) in dying fish compared to surviving fish were observed. Survived fish exposed to 187.5 µg/L showed an increase in hematocrit, MCV, and MCH and a reduction in erythrocytes, total numbers of leukocyte, thrombocyte, lymphocyte, and neutrophil. The fish exposed to concentrations below 125 µg/L, had returned the blood parameter to baselines compared to control. The estimated LC50 was 165.09 µg/L and was classified as highly toxic for the fish tambaqui. In higher concentrations, it causes an acute respiratory toxicity, but in concentrations below 125 µg/L, the fish can adapt to the stressing agent.

Dietary effect of multi-strain prebiotics and probiotics on growth, hemato-biochemical parameters, intestinal histomorphometry, and resistance to hypoxia in juvenile tambaqui (Colossoma macropomum).

This study evaluated the effects of a multi-strain prebiotics and probiotics on the diet of tambaqui Colossoma macropomum. One hundred and fifty juvenile tambaqui (20.2 ± 3.6 g and 10.32 ± 5.78 cm) were randomly distributed in 15 experimental units with a volume of 80 L and fed for 45 days with a diet containing the symbiotic additive at five inclusion levels (0, 2, 4, 6 and 8 g kg feed- 1). At the end of the period, growth performance, survival, hemato-biochemical and intestinal parameters, as well as the fish's resistance to stress were evaluated. The additive did not alter the growth performance, hemato-biochemical and intestinal parameters of the tambaqui. However, the hemato-biochemical parameters of aspartate aminotransferase (AST), plasma protein, hematocrit, glucose, triglycerides and cholesterol showed differences between treatments after the stress challenge. AST increased significantly during challenge and post-challenge. Plasma protein increased significantly during and after the challenge. The hematocrit was highest at 48 h after the challenge and lowest in the 2 g, 6 g and 8 g groups. Glucose was significantly reduced 24 h after the challenge, while triglycerides were lower 24 h and 48 h after the challenge. Cholesterol increased significantly in the challenge. There was an interaction between the factors sampling time and symbiotic concentration for hematocrit and glucose. In hypoxic stress situations, the 2 g concentration was more favorable for the fish. We recommend further studies with 2 g kg feed- 1 in trials lasting more than 45 days.

Effect of temperature on the early sexual development of tambaqui Colossoma macropomum

Effect of temperature on the early sexual development of tambaqui Colossoma macropomum

Production of Late Seedlings of Açai (Euterpe oleraceae) in an Aquaponic System with Tambaqui (Colossoma macropomum, Curvier, 1818)

Over the years, aquaponics has become a powerful technological tool that allows the sustainable production of food, integrating conventional fish farming with vegetable production. The present study evaluated the production of late seedlings of açai Euterpe oleraceae in an aquaponic system with tambaqui Colossoma macropomum. A total of 36 tambaquis with an initial average weight and length of 1086.75 ± 16.38 g and 38.49 ± 0.90 cm were distributed in 12 independent aquaponic units, totaling 3.62 kg m−3. The fish were fed three times daily with commercial feed at a rate of 3%. Three flooding levels of 5, 10 and 15 cm, with constant water flow through the hydroponic bed (0.5 m2), were evaluated, and a control-hydroponic bed with flooding levels of 10 cm was established, all in triplicate. In the 5 and 10 cm treatments, 3450 açai seedlings with an initial height of 12.3 ± 1.9 cm were used (575 per aquaponic units), while the 15 cm treatment contained non-germinated açai seeds. The control group did not receive açai seeds and remained empty. Analyses to monitor total dissolved solids (TDS), electrical conductivity, dissolved oxygen, temperature, pH, alkalinity, hardness, nitrogenous compounds, and phosphate levels were performed. At the end of the 30-day trial, the growth performance of tambaqui and plants was evaluated. Water quality was significantly (p < 0.05) affected by different flooding levels. Electrical conductivity and TDS decreased with an increasing in flooding levels. The flooding levels significantly influenced (p < 0.05) the concentration of total ammonia and nitrate between the treatments. The 5 cm flooding level showed the best plant development indexes for total height, aerial portion height, root height and aerial portion fresh mass. No significant differences (p < 0.05) were observed in tambaqui growth performance. The aquaponic system proved to be effective in reusing fish waste (excreta and feed leftovers) generated in the system. The biotransformation of waste into nutrients allowed the growth of plants and nitrifying bacteria, which, through their metabolic pathways, ensured the purification and reuse of water, avoiding the discharge of this waste into the environment.

Isotopic turnover of carbon δ13C and nitrogen δ15N in the muscle tissue of tambaqui Colossoma macropomum juveniles fed diets containing different levels of digestible protein

The technique that uses natural stable isotopes rises as a safe alternative to evaluate the deposition of potential food constituents’ elements. Diets with distinct isotopic signatures can be used to measure turnover rates in all animal tissues, improving knowledge of metabolic processes in fish nutrition. The aim of the study was to evaluate the growth and turnover of stable isotopes of carbon and nitrogen in the muscle tissue of tambaqui juveniles fed diets containing different levels of digestible protein. A total of 1750 tambaquis were used (weight 6.53 ± 0.43 g and length 7.58 ± 0.18 cm) and distributed in 35 tanks (450 L), with a density of 50 fish per tank. Seven isoenergetic (3378.4 cal g−1) experimental diets were formulated with digestible protein (DP) levels of 14%, 17%, 20%, 23%, 26%, 29% and 32%. During 120 days of experiment, the animals grew over time in all treatments (P < 0.05); and in the evaluated periods, the protein levels of 29% and 32% stood out from the first biometric evaluations, at 30 days, with similar weight averages (P > 0.05) and higher than the averages in the other treatments (P < 0.05). The speed of isotopic changes in muscle tissue was influenced by the characteristics of the diets, and the rates of carbon and nitrogen turnover were more accelerated the higher the protein level. The trial period of 120 days was sufficient for the fish to reflect the isotopic composition of the diets in all treatments (P < 0.05). However, the isotopic contribution of the diet to the tissue as a function of time was different, with indices that reached about 96–97% in 49–63 days of feeding for the diets of 29% and 32% DP and indices of 81–82% for diets of 14% and 17% DP in the same period. The isotopic data analyzed by exponential equations and exploratory analysis showed the formation of three groups with homogeneous characteristics in response to the effects of protein levels: a grouping of diets with 14%, 17% and 20% DP (P > 0.05); another with intermediate levels (23% and 26%); and a third with the highest levels (29% and 32%). Thus, the diet containing 29% of digestible protein proved to be the most attractive for the productive performance of tambaqui juveniles in the growth phase studied.

Prophylactic and therapeutic effects of a nanocomposite (silver nanoparticle plus Terminalia catappa) against Saprolegnia parasitica in tambaqui

Infectious diseases have been the main limiting factor for international fish farming, especially saprolegniosis, which causes large economic losses. Therefore, this study evaluated the prophylactic and therapeutic effect of a nanocomposite (Silver nanoparticle plus extract of Terminalia catappa) to control Saprolegnia parasitica in tambaqui Colossoma macropomum. Two tests were carried out: 1) a therapeutic assay including long and short-term baths, containing two concentrations of nanocomposite each, on infected tambaqui and 2) a prophylactic assay where the zoospore and nanocomposite (four different concentrations) were added at the same time into water for 72 h. Mortality, prevalence index, hematology, and infected areas with S. parasitica on the fish body were evaluated in both tests. In the therapeutic test, all fish from the control group (without nanocomposite) had increased infected area, as well as lethargy and hemorrhage, resulting in 100% mortality. They also had reduced red blood cells, lymphocytes, neutrophils, monocytes, and thrombocytes. In group exposed to nanocomposite, higher concentrations affected mycelial growth, especially in the highest concentration (4.33 mg L−1), reducing infected areas on the fish body by 98.70% and achieving 100% survival. The treatment with long-term bath at the lowest concentration (0.54 mg L−1) had increased values of neutrophils. In the prophylactic test, fish groups without handling stress and the methylene blue had no clinical signs or mortality. However, the fish group submitted to handling stress presented the highest prevalence and infected areas resulting in 100% mortality. However, the increasing of nanocomposite concentration promoted less oomycete prevalence, pathology intensity, and mortality. The most effective concentration in the prophylactic assay was 0.87 mg L−1, preventing the infection without blood alterations. Then, the nanocomposite as prophylactic measured at concentration of 0.87 mg L−1 is the best strategy to prevent S. parasitica infection in fish.

Fish Size Correlates to Size and Morphology of Intermuscular Bones in Tambaqui Colossoma macropomum as Shown by Dissection and X-ray Imaging Methods

One of the main issues in the processing sector of the tambaqui Colossoma macropomum is the removal and/or fragmentation of intermuscular bones (IBs), which negatively impacts its production chain. In this sense, we quantitatively examined the IB variation in farmed tambaqui (n = 127) by comparing the direct anatomical dissection with the high-resolution X-ray imaging method. The number of IBs from the anatomical dissection on the left side of the fish (27.3 ± 5.70 bones) was comparable to that of X-ray analysis (26.9 ± 6.03 bones) (p &gt; 0.05). In addition, 76% of deviation in IB number between the two studied methods was one to three, indicating both methods are equally efficient for identifying and quantifying IBs. We found a strong positive correlation (R = 0.8, p &lt; 0.001) between the X-ray and the dissection methods. Our predictive models indicated that more than 50% of variation in IB length can be explained by growth parameters. Our results demonstrated that the X-ray method can provide accurate phenotypic data (in vivo) for IB counting and length measurements by extrapolating from the standard length, body weight and trunk over axis area of tambaqui.

First record of Neoechinorhynchus buttnerae and Piscinoodinium pillulare infection in Colossoma macropomum in the state of Tocantins, Brazil.

This study aims to report the occurrence of two important parasites in farmed tambaqui Colossoma macropomum in the state of Tocantins, the acanthocephalan Neoechinorhynchus buttnerae and the dinoflagellate protozoan Piscinoodinium pillulare, also suggesting the main treatments to control them. The fish sampled for the study were infected by N. buttnerae, and P. pillulare, with prevalence from 100% and mean intensity from 51.4 to 354,264, respectively. This was the first report on the occurrence of such parasites in C. macropomum in the state of Tocantins. We emphasize the need to adopt good farm management and biosecurity practices to prevent pathogenic agents to enter or leave a property. Reported treatments with synthetic and natural products with positive results are also suggested to treat against those parasites in farmed C. macropomum.

Cardiac response of tambaqui Colossoma macropomum anaesthetised with geraniol and citronellol

Electrocardiographic recordings (ECG) provide information on the duration of the action potential and the heart rhythm. Altered ECG may reflect important disturbances to the cardiac function. The aim of this study was to evaluate putative cardiotoxic effects in Colossoma macropomum upon exposure to geraniol (GRL – 70 μL L−1) and citronellol (CTL – 90 μL L−1) in anaesthetics baths. The fish were randomly distributed across the following treatments: a) control (basal recordings), b) vehicle control (ethanol), c) fish exposed to GRL – 70 μL L−1 and subsequent recovery, and d) fish exposed to CTL – 90 μL L−1 and subsequent recovery, and e) washout from ethanol. Five-minute duration recordings were used. The parameters heart rate (HR) (beats min−1), QRS complex amplitude (mV), R-R interval (s) (time between two successive QRS complexes), Q-T interval (s) (ventricular contraction) and QRS duration (s) (ventricular depolarization) were investigated. No mortality was observed and all animals recovered post exposure. The controls and ethanol-exposed fish presented normal patterns in ECG tracings showing sinus rhythm. Some alterations were observed during induction, e.g., a negative chronotropic effect was observed in fish exposed to GRL, however, with maintenance of the sinus rhythm. Only the Q-T interval was longer than that of the controls. On the other hand, during induction with CTL, marked bradycardia with arrhythmia and prolongation of the Q-T and R-R intervals and QRS complex duration were observed, indicating a potential for atrioventricular blockade. During recovery, albeit slow, all parameters were gradually returning to sinus rhythm, suggesting that although important cardiac changes occurred during induction, mostly with CTL, they did not affect survival. In conclusion, both products induced anaesthesia with full body immobilisation and provoked some cardiac alterations, however, while GRL allowed for a faster recovery, CTL seemed to require a more prolonged time for full resumption of the normal cardiac function.

Effects of thymol:carvacrol association on health and zootechnical performance of tambaqui Colossoma macropomum

Research in aquaculture shows that isomers thymol and carvacrol are extremely promising additives in fish diet, being classified as potent immunostimulant, antioxidant, and growth promoters. In this study, the effects of the thymol:carvacrol combination (1:1 ratio) on health parameters and zootechnical performance of tambaqui (Colossoma macropomum) were evaluated. The compounds were incorporated in concentrations of 0, 500, 1000, 1500, and 2000 mg/kg of feed. At intervals of 30 and 60 days, fish were sampled to evaluate haematological, biochemical, and immunological parameters, and after 60 days, zootechnical performance, parasitic load, and resistance to bacteriosis were evaluated. After 30 days, the fish that received the highest concentrations of thymol:carvacrol showed a reduction in the number of thrombocytes, a decrease in the number of lymphocytes, and an increase in eosinophils (p â"°¤ 0.05). After 60 days of feeding, haematological parameters were similar between all groups. Regarding the antiparasitic effect of the compounds, all groups that received supplemented diets had a high parasitic load (monogenean infestation) that did not differ from the control group. Regarding the prevention of bacteriosis, high mortality was detected in all groups after experimental challenge with Aeromonas jandaei, with no greater protection for fish fed with thymol:carvacrol. In conclusion, it was observed that the haematological results are different from those described in the literature of aquatic animals and corroborate with research of mammals. Therefore, the anti-inflammatory/immunosuppressive action of thymol and carvacrol are highlighted, which is relevant from a pharmaceutical and medicinal point of view. However, the use of these additives for aquaculture deserves to be discussed carefully, as the cost-benefit of this supplementation for the fish farmer is not a consensus.

Cardiac response in tambaqui Colossoma macropomum anaesthetised with Piper divaricatum essential oil

The aim of this study was to evaluate the electrocardiographic responses of Colossoma macropomum exposed to short-term baths using the essential oil of Piper divaricatum (EOPD) as an anaesthetic-like agent in different doses (40, 60, and 80 μL L-1). Cardiac responses throughout and after exposure to EOPD were monitored and evaluated through mean heart rate (HR), duration and amplitude of the QRS complex (ventricular depolarization), and Q-T (ventricular contraction) and R-R (time between two successive QRS complexes) wave intervals. Across all doses, there was a marked depression of the HR, mainly at 80 μL L-1 EOPD. Mean amplitudes recorded for the QRS complex and Q-T interval at 40 μL L-1 EOPD were indistinguishable from the control, which could reinforce this concentration as sufficient and safe to promote fast anaesthesia without affecting cardiac function. Recovery from bradycardia, duration of the R-R interval, and QRS complex were similar at 60 and 80 μL L-1 EOPD; however, the Q-T interval at 80 μL L-1 EOPD revealed a more pronounced cardiac depression in relation to the controls and fish exposed to 60 μL L-1 EOPD. Thus, we conclude that 40 μL L-1 EOPD should suffice to induce fast, deep, and safe anaesthesia in tambaqui juveniles, whereas the concentration of 80 μL L-1 led to a greater depression of the cardiac function, albeit showing effect reversibility.

Impact of high temperature, CO2 and parasitic infection on inflammation, immunodepression and programmed cell death in Colossoma macropomum at the transcriptional level

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 poorly understood, and global warming could pose severe risks to its health as increasing water temperature leads to an increase in the incidence of parasitic diseases. In an experimental context based on the high-emission scenario of the 5th Intergovernmental Panel on Climate Change (IPCC) report, we evaluated the synergistic effect of exposure to the extreme climate change scenario (RCP8.5) during two exposure periods (7 and 30 days) and two levels of parasitism by monogeneans (low and high). The goal was to understand how the tambaqui immune system will react to this challenge. To achieve this goal, we analyzed the expression of nine immunity-related genes (jak3, stat3, il-10, socs1, casp1, il-1β, tp53, bcl2, and hif-1α) in the spleen. Our main findings showed downregulation in the jak3/stat3 pathway, genes related to the control of inflammation and apoptosis, in addition to upregulation of proinflammatory genes and those related to pyroptosis during the first 7 days of exposure to the extreme climate scenario, also indicating a stage of immunodepression in these animals. After 30 days of exposure, all genes tended to return to similar levels in the current scenario, possibly due to the decrease in parasite load caused by chronic exposure to the extreme scenario. Our data strongly suggest that the increase in parasitism intensity caused by the extreme climate change scenario is responsible for disturbances in the host's immune system. However, more studies are needed to clarify this poorly understood cascade of events.

Cold, heat, or double thermal shock in tambaqui (Colossoma macropomum): triploid induction, fertilization rate, growth, and hematological variables

ABSTRACT This study assessed the effectiveness of triploidy in tambaqui (Colossoma macropomum) and compared the fertilization, survival, growth performance, and hematological parameters of diploid and triploid fish. After artificial reproduction, freshly fertilized eggs were subjected to cold, heat or double thermal shock or were not exposed to the thermal shock (control group). Double thermal shock presented fertilization rate significantly lower than other treatments. Larvae submitted to cold thermal shock had a higher weight than the control and heat thermal shock treatments. The final weight of juveniles exposed to cold thermal shock was significantly higher than the other treatments with triploid induction. There was no significant difference for survival and hematological variables. The cold thermal shock produced more triploid individuals (33.33%) than the heat and double thermal shock (both 11.11%). The cold thermal shock was the most effective technique for obtaining triploid fish and it contributed to increasing the weight of tambaqui larvae.

The strategic use of water additives for tambaqui Colossoma macropomum transport: New insights of bacteriosis and productivity approach

The transport of live fish is a major sanitary issue for aquaculture. This study addresses two critical steps regarding natural recurrent mortality outbreaks after transport of tambaqui Colossoma macropomum. At first, five mortality outbreaks post-transport of juveniles showing clinical signs suggestive of columnaris were investigated. Flavobacterium columnare was ascertained as the etiological agent in all outbreaks, causing massive mortality up to 72 h after transport. Based on these findings, the next step consisted of a trial to investigate the use of three additives (8 g/L sodium chloride, 11.12 mg/L Melaleuca alternifolia essential oil and 60 mg/L oxytetracycline) in the water of transport, simulating fish farmers' practices to prevent disease outbreak. Juveniles (≅ 8 cm) were transported for 3 h under trade-mimicking conditions, then transferred to 20 tanks (5 groups, 4 replicates) and monitored for 30 days for analysis of health status. Zootechnical parameters (weight gain, total feed intake, feed conversion, specific growth rate and growth analysis) were assessed on days 1, 15 and 30. The best health status was attributed to the group transported with 0.8% NaCl, which showed 100% survival, in addition to being the only group that did not show behavioral changes and clinical signs, indicating the absence of any infectious biological source after transport. A poly-infection (Aeromonas jandaei and F. columnare) was detected in fish from all other groups (M. alternifolia, oxytetracycline and control). Furthermore, fish exposed to sodium chloride showed better weight gain and feed conversion compared to those transported with oxytetracycline (p ≤ 0.05). Then, the pathogenicity of the two isolated strains (A. jandaei and F. columnare) was ascertained by Koch's Postulate assay, which established two emerging pathogens for C. macropomum. This study addresses fundamental information for the development of fish farming and suggests the addition of salt at 0.8% in the water of transport to prevent columnaris and motile Aeromonas septicemia (MAS) associated disease.

Avaliação da qualidade de pescados amazônicos provenientes de piscicultura armazenados em gelo

The cultivation of natives Amazonian fish such as tambaqui (Colossoma macropomum), pirapitinga (Piaractus brachypomus), tambatinga (female, Colossoma macropomum X Piaractus brachypomus, male) and Pintando da Amazônia (female, Pseudoplatystoma sp. X Leiarius marmoratus, male) temmoratus, increased in recent years, making studies related to the validity of these foods after processing necessary. Therefore, the aimed of the study was to evaluate the sensory, microbiological (Staphylococcus coagulase positive count and presence of Salmonella spp.) and chemical (pH and Total Volatile Bases (TVB) quality of fresh gutted fish stored on ice. Nine specimens of each species were used, all cultivated in an excavated tanks. The fasting time ranged from 16 to 48 hours, depending on the species, the fish was slaughtered by means of cold shock. The fish was gutted and stored in the fish fridge. Sensory analysis was performed by a trained team available. For other analyses, it was sent to a laboratory specializing in food analysis. The sensory analysis of fresh eviscerated tambaqui was characteristic of the species until the 15th day of storage. Fresh eviscerated pirapitinga presented until the 16th day. The fresh eviscerated tambatinga hybrid was kept until the 14th day of storage. And for the Pintado da Amazônia, the organoleptic characteristics were presentable until the 12th day of storage. The microbiological and physical-chemical analyzes were in accordance with Brazilian legislation in all specimens of the analyzed species. It was observed that the longer the fasting period, there was a numerical increase in the pH of the fish meat.

The repertoire of the elongation of very long-chain fatty acids (Elovl) protein family is conserved in tambaqui (Colossoma macropomum): Gene expression profiles offer insights into the sexual differentiation process

Elongation of very long-chain fatty acids (Elovl) proteins are critical players in the regulation of the length of a fatty acid. At present, eight members of the Elovl family (Elovl1–8), displaying a characteristic fatty acid substrate specificity, have been identified in vertebrates, including teleost fish. In general, Elovl1, Elovl3, Elovl6 and Elovl7 exhibit a substrate preference for saturated and monounsaturated fatty acids, while Elovl2, Elovl4, Elovl5 and Elovl8 use polyunsaturated fatty acids (PUFA) as substrates. PUFA elongases have received considerable attention in aquatic animals due to their involvement in the conversion of C18 PUFAs to long-chain polyunsaturated fatty acids (LC-PUFA). Here, we identified the full repertoire of elovl genes in the tambaqui Colossoma macropomum genome. A detailed phylogenetic and synteny analysis suggests a conservation of these genes among teleosts. Furthermore, based on RNAseq gene expression data, we discovered a gender bias expression of elovl genes during sex differentiation of tambaqui, toward future males. Our findings suggest a role of Elovl enzymes and fatty acid metabolism in tambaqui sexual differentiation.

Chemical composition of Lippia Linn. (Verbenaceae) essential oils and their antibacterial potential against Aeromonas spp. isolates from Colossoma macropomum

ABSTRACT The aim of this study was to determine the chemical composition of Lippia alba and two genotypes of L. origanoides, L. origanoides A and L. origanoides B (syn. Lippia sidoides) essential oils(EOs) and to investigate the antibacterial activity against 27 Aeromonas spp. isolated from tambaqui (Colossoma macropomum). The activity of the antibiotics Florfenicol and Oxytetracycline was also compared. The EOs were obtained by hydrodistillation and their composition determined by CG-MS. Antibacterial activity was assessed based in the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) using microdilution method. The main compounds identified were carvone (55.9%) and limonene (21.9%) in L. alba EO, carvacrol (35.6%) and p‐cymene (15.7%) in L. origanoides A EO and thymol (53.5%) and p‐cymene (15.5%) in L. origanoides B EO. The Lippia species showed bacteriostatic and bactericidal action against Aeromonas isolates with MICs and MBCs ranging from 104.17 to 16,666.67 μg.mL−1. Among the tested EOs, the best performance was obtained by that of the L. origanoides B genotype, followed by L. origanoides A and L. alba respectively. Among antibiotics, the best performance was of oxytetracycline (MICs and MBCs ranging from 0.195 to 0.78 μg.mL−1) compared to florfenicol (MICs and MBCs ranging from 0.195 to 3.12 μg.mL−1).