Carlos Eduardo Copatti

Anesthesia of silver catfish with eugenol: time of induction, cortisol response and sensory analysis of fillet

O objetivo deste estudo foi identificar o tempo de inducao e recuperacao anestesica de jundias (Rhamdia quelen) expostos ao eugenol, bem como a eficacia desse anestesico na inibicao do estresse e realizar analise sensorial dos files dos peixes expostos a essa substância. Os jundias foram expostos ao ar por um minuto para realizacao da biometria, e o sangue foi coletado zero, uma e quatro horas depois. O eugenol pode ser usado na faixa de 20-50mg L-1 para a inducao da anestesia em jundias, e o tempo de recuperacao da anestesia nao foi afetado pela concentracao do eugenol. O grupo de controle mostrou niveis significativamente mais elevados do cortisol quatro horas apos a biometria que no tempo zero. Os peixes anestesiados com eugenol (50mg L-1) apresentaram niveis significativamente mais baixos do cortisol plasmatico do que peixes do grupo de controle do mesmo tempo. Esses dados indicam que o eugenol inibe o aumento do cortisol no sangue. O teste sensorial demonstrou que o eugenol modifica o sabor dos files e consequentemente e contra-indicado para a anestesia do jundia quando o file for destinado ao consumo humano.

Freshwater temperature in the state of Rio Grande do Sul, Southern Brazil, and its implication for fish culture

In this study we verified data of water temperatures collected by CORSAN-RS from 1996 to 2004 in several cities of the state of Rio Grande do Sul, southern Brazil, and analyzed the possibility of raising the most cultivated fish species in Brazil. The water temperature from 1996 to 2004 was 16 to 28oC in summer, 17 to 23oC in fall, 14 to 17oC (down to 9oC in the coldest months) in winter and 14 to 21oC in spring. Native species of this state, such as silver catfish (Rhamdia quelen), traira (Hoplias malabaricus), dorado (Salminus brasiliensis), pintado (Pimelodus maculatus), as well as carps (family Cyprinidae), are resistant to the low winter temperatures. These species have a lower growth rate in coldest months (winter/spring) but a good development in warmer months (summer/fall), reaching a satisfactory performance throughout the year. In the periods of more intense cold, mortality of some introduced species, such as surubim from Amazon Basin (Pseudoplatystoma sp.), pirapitinga (Piaractus brachypomus), pirarucu (Arapaimas gigas), pacu (Piaractus mesopotamicus), tambaqui (Colossoma macropomum) and Nile tilapia (Oreochromis niloticus) may occur. In addition, as most tropical species have a thermal range for growth and reproduction between 20 to 28oC, some species may have poor development even in fall. Therefore, water temperature in this state should be considered in the choice of fish species to be cultivated.

Could the essential oil of Lippia alba provide a readily available and cost-effective anaesthetic for Nile tilapia (Oreochromis niloticus)?

Abstract We report the optimal concentration of the essential oil of Lippia alba (EOLA) for the induction and recovery of anesthesia in Nile tilapia (Oreochromis niloticus) during handling. Groups of 10 juveniles were separately subjected to a concentration of EOLA: 0 (control group), 10, 20, 50, 100, 200, 300, or 500 µL L-1. The plasma cortisol levels were significantly decreased in anesthetized fish 4 h after stress of handling. The plasma glucose levels were significantly increased 1 and 4 h after stress of handling in fish exposed to EOLA. Sensory analysis showed that tasters did not detect differences through a blind test in fillet taste and odor between exposed and non-exposed fish. The ideal concentration to promote the best anesthesia and recovery times and to reduce plasma cortisol 4 h after handling is 500 µL L-1.

Low water hardness and pH affect growth and survival of silver catfish juveniles

The objective of this study was to investigate the effects of exposure to low water hardness (0, 25 and 50mg CaCO3L-1) into the 6.0-8.0 pH range to silver catfish juveniles (Rhamdia quelen) survival and growth after 32 days. Juveniles kept at zero water hardness presented higher mortality at pH 7.0 and 8.0 than those submitted to other treatments. Weight of juveniles exposed to pH 6.0 and zero water hardness was significantly higher than those kept at the same water hardness and other pH. Survival and growth of juveniles exposed to 25 and 50mg CaCO3 L-1 was not affected in the 6.0-8.0 pH range. Therefore, the best water hardness for silver catfish juveniles growth is 25-50mg CaCO3 L-1 and at low water hardness (next zero) pH must be reduced.

Uma importante revisão sobre o impacto de agroquímicos da cultura de arroz em peixes

In the rice field, the use of agrochemicals to control rice weeds and pests is recommended to improve yield. However, their use may affect non-target organisms, as the fishes. Therefore, this review has like objective to analyze data regarding the effects of agrochemicals used in the rice field in fishes to propose strategies to minimize their impact. There is a large variation in the agrochemicals toxicity, and the determination of the medium lethal concentration in 96 hours is only an initial approach for additional studies, because many of them can provoke changes in biochemical parameters in fish tissues at lower concentrations. These biochemical parameters are more appropriate as biomarkers for agrochemicals. It is suggested to use the minimum recommended dose to minimize the impact of the agrochemicals, as well as to keep the water layer of the rice field for at least two weeks after the application to decompose the active principle and reduce toxicity. Besides, the integrated pest management is recommended, even as the rice-fish culture, which avoids the use of agrochemicals and in some situations, may give similar yields.

Ictiofauna da microbacia do Rio Jaguari, Juaguari/RS, Brasil

The microbasin of the Jaguari river belongs to the hydrographic basin of the River Uruguay and has its estuary in the raised edge of the river Ibicui. This work had the objectif identify the existing ictyofaun of the microbasin of the river Jaguari in Jaguari-RS. For the accomplishment of the research identifications of units captured in the four months of the year had been carried through, being that nets of wait of each one of following meshes (measured in cm between adjacent points): 1.0; 1.5; 2.0; 2.5; 3.0; 4.0; 5.0; 6.0; and 7.0. The wait nets had remained in the water for 24 hours, being revised to each six hours, always in same periods (06:00 AM; 12:00 AM; 06:00 PM and 12:00 PM hours). The collected fish, after to be identified, had been numbered and then after, fixed in formaldehyde conserved 4.0% and later in alcohol 70.0%. A total of 572 individuals in the four stations of the year were identified, distributed in 14 families and 26 species. In the spring the biggest capture occurred, with 156 individuals, distributed in 15 species; in the period of summer the biggest richness occurred, with a capture of 146 individuals distributed in 19 species; in the autumn and winter a capture of 135 individuals for both occurred the stations, with a richness of 16 and 12 species, respectively. The species most abundant, with 291 units, was Apareiodon affinis, being that Hemiancistrus fuliginosos (75), Hypostomus commersoni (50) and Steindachnerina brevipina (41) also had high representation.

Morphological variation in the sexual maturity of three sympatric aeglids in a river in southern Brazil

The objective of this study was to investigate the use of morphometric aspects of three sympatric aeglids (Aegla platensis, Aegla grisella, and Aegla ludwigi) to determine the mean size of males and females at the onset of sexual maturity and verify whether there are differences at sexual maturity between the species. The relationships between CL and cheliped dimensions for males and CL and AW for females reflecting the onset of morphological sexual maturity were tested using the software REGRANS. The intersections between the lines of allometric growth for juveniles and adults were tested using an analysis of covariance (ANCOVA). In males and females, the growth rate was positively allometric. The analysis of juveniles and ovigerous females showed that they breed year round. The three sympatric aeglids reached the onset of sexual maturity at different sizes, which may facilitate the coexistence of all species.

Variação sazonal e diversidade de peixes do rio Cambará, Bacia do rio Uruguai

The aim of this study was to analyze the ictiofaun of Cambara River, Uruguay Basin, as well as the body dimensions of the organisms. The work was accomplished in two stretches of Cambara River (2nd order) in Cruz Alta, RS. To the accomplishment of this research were performed identifications of individuals captured in May, September and November 2009 and February 2010 by using of gillnets, which remained in water for 24 hours, being checked every eight hours (1:00 and 9:00 AM and 5:00 P.M.). Besides the gillnets, were also used trawl (mesh 1.0 mm), and fishing rods. The fish collected were cataloged and fixed in formaldehyde at 10.0% and then conserved in alcohol 70.0%. In total, 420 individuals were identified, with a richness of 26 species and eight families. The species were classified in: constant (23.08%), accessory (42.31%) and accidental (34.61%). Loricariidae (nine species and 156 individuals) and Characidae (seven species and 136 individuals) were the most typical. Among individuals collected are highlighted as more abundant: Hemiancistrus fuliginosus (89), Astyanax eigenmanniorum (50), and Rhamdia aff. quelen (44). One recorded species was of large mien (Hoplias lacerdae, with 164.92 g total weight and 23.40 cm total length), five medium sized species (98.55-164.92 g total weight and 19.56-21.50 cm total length) and 20 small species (less than 57.79 g total weight and 17.38 cm total length). The diversity was higher in hotter months, mainly between 1:00 and 9:00 A.M. The collector curve showed that still exist species of fish for being collected in Cambara River. Concluding that despite of the existence of environmental impacts in the stretch of study, it showed satisfactory diversity and richness, influenced by factors like heterogeneity of habitats and supply of allochthonouss material, as well as intrinsic factors (activity and reproduction) to the present species.

Calcium fluxes in Hoplosternum littorale (tamoatá) exposed to different types of Amazonian waters

Os peixes que vivem na Amazonia sao expostos a varios tipos de agua: aguas pretas, contendo grande quantidade de carbono orgânico dissolvido, aguas brancas, com concentracao de Ca2+ dez vezes maior que as aguas pretas e pH neutro, e aguas claras, com concentracao de Ca2+ duas vezes maior que as aguas pretas e pH tambem neutro. Dessa forma, o objetivo deste trabalho foi analisar o fluxo de Ca2+ no peixe de respiracao aerea facultativa Hoplosternum littorale (tamoata) exposto a diferentes tipos de aguas amazonicas. Os peixes foram aclimatados em agua de poco artesiano (semelhante a agua clara) e depois colocados individualmente em câmaras para medir o fluxo de Ca2+. Apos 4 h, a agua das câmaras foi trocada por um tipo diferente de agua. A transferencia do tamoata das aguas pobres em ions agua preta e preta acida ou da agua branca, rica em ions, para as aguas preta e preta acida, pobres em ions, resulta em uma perda de Ca2+ apenas nas duas primeiras horas de experimento. Entretanto, a transferencia da agua preta e preta acida, para a agua branca resulta em um influxo de Ca2+. Os resultados obtidos nos permitem concluir que a transferencia do tamoata para as aguas preta e preta acida, pobres em ions, leva a uma temporaria perda de Ca2+, e a quantidade de Ca2+ na agua branca, rica em ions, e adequada para prevenir sua perda apos a transferencia. Sendo assim, a transferencia do tamoata entre as aguas estudadas nao resulta em serios disturbios no Ca2+.

Essential oil of Aloysia triphylla is effective in Nile tilapia transport

The study evaluated the use of the essential oil of Aloysia triphylla (EOAT) as stress reducer in transporting Nile tilapia, Oreochromis niloticus. Juveniles were transported for 8 h in plastic bags by car with water containing 0 (control), 20 or 30 μL L-1 EOAT (three replicates). We evaluated water quality, net ion fluxes (Cl−, Na+ and K+) and, plasma parameters (cortisol, glucose, lactate and paraoxonase) and ventilatory rate (VR) of Nile tilapia. There was no mortality in juveniles undergoing transport. Nile tilapia transported with 20 or 30 μL L-1 EOAT presented lower pH than control group and with 30 μL L-1 EOAT presented lower water conductivity, alkalinity and Cl−, Na+ and K+ net ion fluxes compared to other treatments. The EOAT did not alter plasma cortisol and paraoxonase levels, but reduced VR, and 30 μL L-1 EOAT reduced plasma glucose levels compared to the control group after transport. The use of 20 μL L-1 EOAT increased plasma lactate levels compared to other treatments. The use of 30 μL L-1 EOAT for sedation in 8 h transport of Nile tilapia is recommended because it improved water quality and reduced ionic losses, plasma glucose levels and VR.