Efficacy of essential oil from ginger (Zingiber officinale) for anesthesia and transport sedation of pacu (Piaractus mesopotamicus).

This study evaluated the anesthetic and sedative effects of the essential oil of Zingiber officinale (EOZO) on juvenile pacu (Piaractus mesopotamicus). Experiment 1 evaluated concentrations of 0, 50, 100, 200 and 400 mg L-1 EOZO for times of induction and recovery from anesthesia. Furthermore, hematological responses and residual components of EOZO in plasma were determined immediately after anesthesia. Experiment 2 evaluated the effect of 0, 10, 20 and 30 mg L-1 EOZO on water quality, blood variables and residual components of EOZO in plasma and tissues (muscle and liver) immediately after 2 h of transport. Survival was 100%. The three main compounds of EOZO [zingiberene (32.27%), ß-sesquiphellandrene (18.42%) and ß-bisabolene (13.93%)] were observed in animal plasma and tissues (muscle and liver) after anesthesia and transport, demonstrating a direct linear effect among the evaluated concentrations. The concentration of 200 mg L-1 EOZO promoted surgical anesthesia of pacu and prevented an increase in monocyte and neutrophil levels, yet did not alter other hematological parameters. The use of 30 mg L-1 EOZO has a sedative effect on juvenile pacu, thereby reducing oxygen consumption during transport. Furthermore, the use of 30 mg L-1 EOZO in transport water prevented an increase in hemoglobin and hematocrit, with minimal influences on other blood variables.

Rearing and maturation of Lophiosilurus alexandri (Steindachner, 1876) in controlled conditions: First reports and future perspective.

Lophiosilurus alexandri is a freshwater carnivorous fish for which there is fishing pressure in its natural environment, yet the species has potential for captive rearing. Information on growth and sexual development for the species is scarce, and age and size at first maturation have yet to be determined. A total of 400 fish, therefore, were reared from hatching to 968 days after hatching (DAH). Fish gonads were histologically analyzed throughout the rearing period, and growth, the hepatosomatic index and the gonadosomatic index were compared between males and females. Estradiol, testosterone and 17α-hydroxyprogesterone concentrations were quantified at 845 and 968 DAH to compare sexually mature males and females. Weight and length did not differ between males and females (P >  0.05). Males were sexually mature at 593 DAH, with body lengths of 29.88 ±â€¯1.76 cm and weights of 444.1 ±â€¯77.03 g, while females were sexually mature at 845 DAH, with lengths of 36.51 ±â€¯1.06 cm and body weights of 783.05 ±â€¯48.57 g. The results provided important information regarding the minimum capture size of L. alexandri for identifying the appropriate period to begin reproductive management of the species.

Response of juvenile Lophiosilurus alexandri to osmotic and thermic shock.

The objective of the present study was to evaluate the physiological responses of juvenile Lophiosilurus alexandri submitted to osmotic and thermic shock. Thirty juveniles were used for each test, of which 10 were not subjected to stress and remained in normal conditions (fresh water at 28.0 °C). The others were submitted to stress shock (saline water of 10.0 g of salt/L or water cooled to 18.0 °C). Blood samples were taken at 0 h (no exposure to the stress factor) and 1 h and 24 h after the tests. At 24 h, the survivorship was 100% in both tests. In both the osmotic and thermic shock tests, cortisol and glucose levels were higher at 1 h but then decreased after 24 h. Lactate dehydrogenase showed differences in the temperature test, but there was no difference between 1 and 24 h after exposure to osmotic shock (P > 0.05). The difference was recorded in blood gas variables (pH, PvCO2, PvO2, hemoglobin, sO2, BE, tCO2, HCO3-, and stHCO3-) and electrolytes (Na+, Ca++, nCa++, and K+) in both experiments. With regard to hematology and blood biochemistry, exposure to thermal shock did not affect (P > 0.05) ALP, total plasma protein, hematocrit, and ALT and AST at 1 h and 24 h. ALP and total protein in the blood of fish submitted to the osmotic shock were lowest (P < 0.05) at 24 h. Leukocyte and erythrocyte counts exhibited differences after osmotic shock, in contrast to erythrocyte counts of the temperature test, which did not change in 24 h (P > 0.05). Juveniles of L. alexandri were able to reestablish the main indicators of stress (cortisol, glucose), while the others (hematological, biochemical, and gasometric) varied in compensation for normal physiological reestablishment.

Physiological and metabolic responses of juvenile Lophiosilurus alexandri catfish to air exposure.

The present study aimed to evaluate the physiological and metabolic stress responses of juvenile Lophiosilurus alexandri submitted to an air exposure test. The subjects consisted of 72 juveniles. Blood samples were taken at: 0 h-fish not exposed to air; 0.5 h-fish shortly after exposure to air for 30 min (prior to returning to the tank); 1.5 h (90 min), 24, 48, and 96 h after the initiation of exposure to air for 30 min. After 96 h, survivorship was 100%. Cortisol and glucose levels were higher at 0.5 h, returning to baseline at 48 and 24 h, respectively. Lactate dehydrogenase levels were highest at 1.5 h after exposure to air, returning to normal values in 24 h. Several changes were recorded in gasometric blood values and electrolytes. With regard to hematology and blood chemistry, exposure to air did not affect globular volume and AST throughout the 96 h of the experiment. The values for alkaline phosphatase were highest at 0, 1.5, and 24 h. Total protein was similar between 0 and 1.5 h and lowest at 96 h, while ALT was highest at 0.5 h. Leukocytes were highest at 0.5, 1.5, 48, and 96 h, while erythrocytes were highest at 96 h. After 96 h, juvenile L. alexandri were able to reestablish the main indicators of stress (cortisol, glucose and lactate dehydrogenase), while other indicators (hematological, biochemical, and gasometric) exhibited compensatory variation for normal physiological re-establishment.

Biological responses of Neotropical freshwater fish Lophiosilurus alexandri exposed to ammonia and nitrite.

This study aimed to elucidate the responses of the Neotropical fish Lophiosilurus alexandri exposed to ammonia and nitrite, following a period of recovering. Acute toxicity tests lasted 96h, subchronic toxicity tests lasted eight days and the detoxification trial lasted four days. Groups of 12 juveniles were maintained in 90-L tanks and treated with increasing concentrations of ammonia and nitrite, except during the recovery test. All treatments were performed with two replicates. The median lethal concentrations (LC50) of 24, 48, 72 and 96h were estimated at 30.12; 24.35; 19.24 and 18.68mg·L-1 TA-N; 5.37; 4.57; 3.75 and 3.66mg·L-1 NH3-N and 20.37; 7.78; 7.09 and 5.86mg·L-1 NO2--N, respectively. The NO2- caused significant decrease in hematocrit and increase in the urea levels during short-term exposure, with recovery of homeostasis after the subchronic and detox period. Acute exposure to ammonia increased the enzyme profile of transaminases, glucose and urea. Urea concentration remained high in the subchronic and detox tests. Histopathologies were observed in animals exposed to ammonia in both toxicity tests. It was highlighted detachment of epithelium, hyperemia and necrosis in the gills. Exposure to NO2- caused epithelium detachment and aneurysm. Vacuolization and swelling of hepatocytes were the most common injury for both nitrogenous compounds. We concluded that the L. alexandri has moderate tolerance to ammonia and nitrite. The recovery period revealed remedial response to ammonia and nitrite exposure.

The influence of the photoperiod on productive performance and survival of piabanha-of-Pardo (Brycon vonoi ), hatchery / Influência do fotoperíodo no desempenho produtivo e sobrevivência na criação de larvas de piabanha-do-Pardo (Brycon vonoi)

ABSTRACT: This research aimed to verify the influence of the photoperiod on the performance and survival piabanha-of-Pardo (Brycon vonoi) larvae. Piabanha-of-Pardo larvae 24 hours post-hatch, with body weight of 2.44 ± 0.02mg, and total length of 7.82 ± 0.46mm, were subjected to five different photoperiods: 0L:24D, 6L:18D, 12L:12D, 18L:6D and 24L:0D (871.12 ± 92.65 lux). Daily, the water temperature, dissolved oxygen (DO), percentage of oxygen saturation, pH, and water conductivity were monitored, and presented similar water quality values among tanks with distinct photoperiods, and within the range considered appropriate for the genus Brycon larvae. Piabanha-of-Pardo larvae have better productive performance and survival rate at longer photoperiods, over 6 hours of light and below 12 hours of light per day. The 9L:15D photoperiod, specified by the derived equation, is indicated for the piabanha larviculture, but researches with the species and the photoperiod need to be better studied.

RESUMO: Este trabalho apresenta como objetivo verificar a influência do fotoperíodo sobre o desempenho e sobrevivência de larvas piabanha-do-Pardo (Brycon vonoi). As larvas de piabanha-do-Pardo com idade de 24h pós-eclosão, com peso corporal de 2,44 ± 0,02mg, e comprimento total de 7,82 ± 0,46mm, foram submetidas a cinco diferentes fotoperíodos: 0L:24E, 6L:18E, 12L:12E, 18L:6E e 24L:0E (871,12 ± 92,65 lux). Diariamente a temperatura da água, oxigênio dissolvido, percentagem de saturação de oxigênio, pH, e condutividade da água foram monitorados. Estes apresentaram valores similares entre os aquários com distintos fotoperíodos, e dentro da faixa considerada, adequada para as larvas do gênero Brycon. As larvas de piabanha-do-Pardo apresentam melhor desempenho produtivo e taxa de sobrevivência em fotoperíodo mais longos, acima de 6 horas de luz e abaixo de 12 horas de luz. O fotoperíodo de 9L:15E, especificado pela equação derivada, é indicado para a larvicultura da piabanha, mas as pesquisas com a espécie e o fotoperíodo precisam ser melhor estudadas.

Description of amino acid and fatty acid content during initial development of Lophiosilurus alexandri (Siluriformes: Pseudopimelodidae), a carnivorous freshwater catfish

Samples of eggs, newly hatched larvae (NHL), and larvae at the end of the lecithotrophic period (eight days after hatching) (LPL) of Lophiosilurus alexandri were collected to determine the amino acid and fatty acid profiles. Crude protein did not change throughout initial development and the concentration of lipids was highest in NHL. The content of the indispensable amino acids (IAA) isoleucine, leucine, and valine decreased in LPL, while in eggs and NHL they remained high and similar in value. The dispensable amino acids (DAA), such as aspartic acid, tyrosine, and glycine, increased in LPL, while alanine decreased. The percentage of neutral lipids increased in LPL. The saturated fatty acid content decreased during ontogeny, while monounsaturated fatty acids decreased only in LPL. The polyunsaturated fatty acid content was highest in LP. Polar fatty acids were found in higher percentages in eggs and NHL, but lower in LPL. Saturated fatty acid content decreased during ontogenetic development, while that of monounsaturated fatty acids decreased only in LPL. Polyunsaturated fatty acid content was highest in LPL. Protein content was maintained during ontogenetic development, while amino acid classes experienced changes. Lophiosilurus alexandri preferentially uses saturated and monosaturated fatty acids as an energy source during its early development.(AU)

Amostras de ovos, larvas recém-eclodidas (NHL) e larvas no final do período lecitotrófico (oito dias após a incubação) (LPL) de Lophiosilurus alexandri foram coletadas para determinar os perfis de aminoácidos e ácidos graxos. A proteína bruta não alterou durante o desenvolvimento inicial e a concentração de lipídios foi maior na NHL. O conteúdo dos aminoácidos indispensáveis (IAA) isoleucina, leucina e valina diminuíram em LPL, enquanto nos ovos e NHL eles permaneceram com valores elevados e semelhantes entre si. Os aminoácidos dispensáveis (DAA), como ácido aspártico, tirosina e glicina, aumentaram em LPL, enquanto a alanina diminuiu. A porcentagem de lipídios neutros aumentou em LPL. O teor de ácidos graxos saturados diminuiu durante a ontogenia, enquanto os ácidos graxos monoinsaturados diminuíram apenas em LPL. O teor de ácidos graxos poliinsaturados foi maior em LPL. Os ácidos graxos polares foram encontrados em porcentagens mais altas em ovos e NHL, e menores em LPL. O teor de ácidos graxos saturados reduziu durante o desenvolvimento ontogenético, enquanto que os ácidos graxos monoinsaturados diminuíram apenas em LPL. O teor de ácidos graxos poliinsaturados foi maior em LPL. O conteúdo de proteínas foi mantido durante o desenvolvimento ontogenético, enquanto as classes de aminoácidos sofreram mudanças. Lophiosilurus alexandri usa preferencialmente ácidos graxos saturados e monossaturados como fonte de energia durante o desenvolvimento inicial.(AU)

Description of the composition of fatty acids and lipids in the breeders muscle, oocytes and in the embryonic development of Brycon orthotaenia (Günther, 1864).

The objective of this work was to evaluate the fatty acid and lipid composition of oocytes, newly hatched larvae (NHL), first feeding larvae (FFL) and muscle tissue of female Brycon orthotaenia broodstock. Total and polar lipid was significantly (P<0.05) abundant in oocytes and larvae in different stages of development. The lowest content (P<0.05) of total lipids was found in the muscles, whereas total lipid content of oocytes, NHL and FFL did not show any significant difference. Polar lipid content was different (P<0.05) between NHL and FFL. For the neutral the lowest values of C18:2n 6 occurred during the initial feeding period, whilst C20:4n 6 (AA) exhibited the highest percentage in FFL (P<0.05). C22:6n 3 (DHA) was highest (P<0.05) in FFL. The neutral lipid n-9 and n-6 was highest in muscle of females. The n-3HUFA was highest in NHL and in FFL, n-6HUFA was highest in FFL (P<0.05). The ratios of DHA/EPA were higher (P<0.05) in oocytes and FFL. In fatty acids of polar lipids, C20:5n 3 (EPA) did not show differences (P>0.05) between stages. C18:3n 3 was highest (P<0.05) in NHL and FFL. C20:4n 6 (AA) and C22:6n 3 (DHA) showed the highest percentages during the larval stages. The fatty acids n-3 series was significantly higher (P<0.05) in FFL. The n-6HUFA was highest during development larval (P<0.05). The increases DHA reflects the ability of the species to elongate and desaturate to obtain n-3HUFA from 18:3n 3, shows the importance of this fatty acid during early development.

Early sexing techniques in Lophiosilurus alexandri (Steindachner, 1876), a freshwater carnivorous catfish.

This study aimed to evaluate sexing techniques for juvenile Lophiosilurus alexandri. With this aim, we evaluated three techniques: coelioscopy, performed with the use of video surgery equipment; coeliotomy, a surgical procedure for direct visualization of the gonads; and sex determination using a urethral probe to compare the genital papillae. For coelioscopy, the survival rate was 100% 30 days after the procedure, and the fish restarted eating 10 days after surgery. This technique resulted in a 100% correct identification of individuals identified as females, whereas for males, it was 66.6%. There was no significant difference between males and females for anesthesia induction and recovery times. However, the procedure took longer for males because of the difficulty in observing the gonads, which can be attributed to the large amount of visceral fat in males. Coeliotomy also resulted in a 100% survival rate 30 days after surgery, and the efficiency of this technique was 96.3% for males and 93.9% for females. The fish restarted eating between 10 and 14 days after surgery, and there were no significant differences between males and females for anesthesia induction and recovery times for the surgical procedure to visualize the gonads (P > 0.05). The urethral probe technique was less efficient with an accuracy rate of 67.8% and 81.8% for males and females, respectively. We conclude that coeliotomy was more efficient for sexing both sexes of juvenile L. alexandri.

Capture, adaptation and artificial control of reproduction of Lophiosilurus alexandri: A carnivorous freshwater species.

The present study describes the capture adaptation and reproduction of wild Lophiosilurus alexandri broodstock in laboratory conditions. There were two periods when capturing was performed in natural habitats. The animals were placed in four tanks of 5m(3) with water temperatures at 28°C with two tanks having sand bottoms. Thirty days after the temperature increased (during the winter) the first spawning occurred naturally, but only in tanks with sand on the bottom. During the breeding season, there were 24 spawning bouts with egg mass collections occurring as a result of the spawning bouts that occurred in the tanks. The hatching rates for eggs varied from 0% to 95%. The spawning bouts were mainly at night and on weekends. In the second reproductive period, the animals were sexed by cannulation and distributed in four tanks with all animals being maintained in tanks with sand on the bottom at 28°C. During this phase, there were 36 spawning bouts. Findings in the present study contribute to the understanding of the reproductive biology of this endangered species during captivity.

Effect of water temperature and prey concentrations on initial development of Lophiosilurus alexandri Steindachner, 1876 (Siluriformes: Pseudopimelodidae), a freshwater fish

The aim of this study was to investigate the effects of water temperature and prey concentrations (Artemia nauplii) on the initial development of Lophiosilurus alexandri larvae. The experiment was conducted using a 4 x 2 factorial design, with four water temperatures (23, 26, 29 and 32 °C), two different initial prey concentrations (P700 and P1,300) and three replicates. Feeding was increased during the fifteen-day experiment. At the end of the experiment, the survival and condition factor were affected only by prey concentrations, with elevated numbers of Artemia nauplii leading to higher averages of these variables. The total length (TL) and specific growth rate were separately influenced by temperature and prey concentration, without interaction between them, and weight showed an interaction with these factors. In general, an increase of temperature (23 to 32 °C) improved the growth and nitrogen gain in L alexandri larvae. For TL, the optimal temperatures estimated were 31.4 and 31.0 °C for P700 and P1,300, respectively. Similar mean body weight larvae and nitrogen gain were observed at 23 °C for both levels of prey concentrations. For other temperatures, the P1,300 level provided greater weight gain for L. alexandri. Therefore, it is suggested that temperatures between 29-32 °C combined with a higher level of prey concentration maximise the development and nitrogen gain in L. alexandri larvae. Moreover, this is the first result about nitrogen incorporation in neotropical fish larvae.

O objetivo deste estudo foi investigar os efeitos da temperatura da água e concentrações de presas (náuplios de Artemia) no desenvolvimento inicial de larvas de Lophiosilurus alexandri. O experimento foi conduzido em esquema fatorial 4 x 2, com quatro temperaturas da água (23, 26, 29 and 32 °C), duas concentrações de presas (P700 e P1.300) e três réplicas. A quantidade de alimento ofertado aumentou durante os 15 dias de experimento. Ao final do experimento a sobrevivência e o fator de condição foram afetados apenas pela concentração de presas, sendo que a maior concentração proporcionou médias superiores para as variáveis mencionadas. O comprimento total (CT) e a taxa de crescimento específico foram influenciados separadamente pelos fatores temperatura e concentração de presa, sem interação entre os fatores, e o peso individual das larvas apresentou interação entre os fatores estudados. Em geral, o aumento da temperatura (de 23 para 32 °C) promoveu o crescimento e o ganho em nitrogênio nas larvas de L alexandri. Para o CT, a temperatura ótima ficou em 31,4 e 31,0 °C para P700 e P1.300, respectivamente. Médias semelhantes do peso individual e ganho em nitrogênio foram observadas nos animais cultivados a 23 °C em ambos os níveis de concentração de presas. Nas demais temperaturas, o nível de P1.300 levou a um maior ganho em peso para as larvas de L. alexandri. Desta forma, conclui-se que o desenvolvimento inicial das larvas de L. alexandri é afetado por ambos os fatores estudados, e temperaturas entre 29-32 °C combinados ao maior nível de concentração de presas são as melhores opções para maximizar o desenvolvimento das larvas e o ganho em nitrogênio. Em adição, esse é o primeiro resultado sobre a incorporação de nitrogênio em larvas de peixes neotropicais.