Deliane Cristina Costa

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.

Frequência alimentar e taxa de arraçoamento durante o condicionamento alimentar de juvenis de pacamã

The objective of this work was to evaluate feeding frequency and rate during feed training of pacama juveniles. Feeding for three or four times a day and the feeding rates at 50, 75 and 100% of biomass were tested. Feeding management did not affect fish growth, survival, mortality, and cannibalism. Lack of management effect was kept when animals were fed extruded feed threefold a day, during 30 days. Feeding rate at 50% of biomass and threefold-a-day feeding can be used for the feed training of pacama juveniles.

Larvicultura de piabanha-do-pardo em aquários de cores diferentes

The objective of this work was to evaluate the effect of different colors of aquariums on the larviculture of piabanha-do-pardo (Brycon sp.). The treatments consisted of the use of light- (white, green, and blue) and dark- (brown and black) colored aquariums. At the end of the experiment, survival, weight, total length, and color of the larvae were measured and compared by the Tukey test, at 5% probability. Survival was lower (66.25%), with a higher rate of cannibalism (17.08%), in the blue-colored aquarium when compared to the brown-colored one (84.17%), with a low rate of cannibalism (6.25%). Total length, weight, and mortality did not differ among treatments. The color of the larvae gradually darkened from the lighter to the darker aquariums, which interfered with cannibalism and survival. The brown aquarium promotes a greater survival value and a lower rate of cannibalism in larvae of piabanha-do-pardo.

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 effect of environmental colour on the growth, metabolism, physiology and skin pigmentation of the carnivorous freshwater catfish Lophiosilurus alexandri

The growth, physiology and skin pigmentation of pacamã Lophiosilurus alexandri juveniles were evaluated in an experiment using different tank colours (white, yellow, green, blue, brown and black) over an 80 day period. The tank colours did not cause significant differences to final body mass, total length, survival rate, carcass composition (moisture, crude protein, ash, ether extract, calcium, phosphorus, energy), or to plasma protein, triglyceride and cholesterol values. Haematocrit values, however, were highest for fish kept in white tanks (ANOVA P < 0·05), while the greatest haemoglobin levels were recorded for fish kept in blue and brown tanks (P < 0·01). The concentrations of cortisol (P < 0·001) and glucose (P < 0·01) were the most in fish in the black tanks. Tank colour affected skin pigmentation significantly, with fish in white tanks having the highest values of L* (brightness) and the lowest values in blue and black tanks. L*, however, decreased in all treatments throughout the experiment. C*ab increased significantly over the course of the experiment in fish kept in white tanks. Similar increases of C*ab were recorded in the other treatments but to a lesser extent. The use of black tanks during the cultivation of L. alexandri caused stress and should be avoided. Cultivation in white and yellow tanks produced individuals with a pale skin colour, while cultivation in blue and black tanks resulted in juveniles with a darker and more pigmented skin.

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)

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.