Can photoperiod improve growth performance and antioxidant responses of pacu (Piaractus mesopotamicus) reared in recirculation aquaculture systems?

The present study investigated the best photoperiod for culturing pacu (Piaractus mesopotamicus) in recirculation aquaculture systems (RAS) based on its growth performance and hematological and oxidative stress responses. Juveniles (∼ 5 g) were subjected to five treatments (in triplicate): 24 L (light):0D (dark), 15 L: 09D, 12 L:12D, 9 L:15D, and 0 L:24D for 45 days. A total of 225 pacu individuals were randomly distributed among 15 tanks of 210 L (n = 15 per tank). Zootechnical, hematological (glucose, lactate, hematocrit, and hemoglobin), and antioxidant and oxidative stress parameters (glutathione S-transferase (GST), total antioxidant capacity against peroxyl radicals (ACAP), and lipid peroxidation (LPO) were analyzed. The zootechnical parameters (e.g., weight gain, Fulton's condition factor, and specific growth rate) were better and worse with 9 L:15D and 24 L:0D photoperiods, respectively. The hepatosomatic index was higher and lower in the 0 L:24D and 9 L:15D photoperiods. Blood lactate levels and antioxidant and oxidative stress responses were increased in the longest photoperiods (15 L:9D and 24 L:0D). In contrast, the treatments that showed lower oxidative damage (liver, gills, brain, and muscle) were 9 L:15D and 12 L:12D. In conclusion, manipulating artificial light is one way to improve fish growth and health, where the best photoperiod for pacu farming in RAS is 9 L:15D.

Responses to graded levels of zinc amino acid complex in Nile tilapia (Oreochromis niloticus).

Zinc (Zn) is an essential micronutrient that plays a crucial role in fish development and physiology. This study aimed to evaluate the effects on growth and health in Nile tilapia (Oreochromis niloticus) supplemented with graded levels of zinc amino acid complex (Zn-AA) and subjected to transport stress. Nile tilapia (21.78 ± 0.17 g; (n = 12 fish per tank; stocking density of 1.045 kg- 3) were fed with 0, 25, 50, 75, or 100 mg Zn-AA kg- 1 (equivalent to 77.49, 102.69, 127.89, 153.09, or 178.29 mg Zn kg- 1) in extruded diets (280 g kg- 1 digestible protein; isoproteic and isocaloric) for 60 days. At the end of the experimental period, after growth performance measurements, the fish were transported by car for 3 h, and blood collection was performed. The linear regression showed that the best growth performance (final weight, final biomass, weight gain, specific growth rate, and feed intake) was found in fish fed with 100 mg Zn-AA kg diet- 1 (p < 0.05). The increased dietary Zn-AA increased linearly plasma triglyceride levels, hemoglobin, mean corpuscular hemoglobin, and leukocyte values and reduced plasma total protein, cholesterol (total and LDL), and aspartate aminotransferase levels (p < 0.05). According to quadratic regression, the highest plasma glucose and alanine aminotransferase values were found in the control group (p < 0.05). In conclusion, under the conditions of this study, 100 mg Zn-AA kg diet- 1 is recommended for Nile tilapia as it can improve their growth, metabolism, physiology, and immunity.

Assessment of methionine plus cystine requirement of tambaqui (Colossoma macropomum) based on zootechnical performance, body composition, erythrogram, and plasmatic and hepatic metabolites.

Tambaqui (Colossoma macropomum) is a species of great cultural and economic importance in aquaculture in the Amazon region. Methionine is considered the first limiting sulfur amino acid in practical fish diets, which encourages investigating its use in diets for tambaqui. This study aimed to verify the digestible methionine plus cystine (Met + Cys) requirement in diets for tambaqui (89.52 ± 0.53 g) for 60 days. The treatments investigated were: 6.50, 7.80, 9.10, 10.40, 11.70, and 13.00 g Met + Cys kg diet-1. The estimated requirement based on final weight, weight gain, feed conversion ratio, and specific growth rate was 9.04, 8.92, 8.91, and 8.58 g Met + Cys kg diet-1, respectively, while on body protein deposition, body fat deposition, body ash deposition, and nitrogen retention efficiency was 9.29, 9.20, 9.19, and 8.72 g Met + Cys kg diet-1, respectively. Linear regression demonstrated that increased digestible Met + Cys in the diet decreased plasma total protein, globulin, and liver total protein levels. Quadratic regression showed that the highest value for liver glycogen was found with a 10.40 g Met + Cys kg diet-1. Another quadratic regression demonstrated a lower hepatic aspartate aminotransferase (AST) enzymatic activity in fish fed between 7.80 and 11.70 g Met + Cys kg diet-1. The different treatments did not influence the erythrogram. In conclusion, when considering an integrative view of the results for growth performance, whole-body deposition, and liver parameters without harming the physiological and metabolic status, we recommended choosing a diet with digestible Met + Cys between 8.58 and 9.29 g kg- 1 for tambaqui.

Essential oils from Cymbopogon citratus and Lippia sidoides in the anesthetic induction and transport of ornamental fish Pterophyllum scalare.

This study verified the effects of essential oils from Lippia sidoides (EOLS) and Cymbopogon citratus (EOCC) on the anesthesia of freshwater angelfish (Pterophyllum scalare) of two different sizes (juveniles I (0.82 g) and II (2.40 g)) and the transport (8 h) of juveniles II. Fish were exposed to different concentrations of EOLS and EOCC: 0, 10, 25, 50, 75, 100, 150, 200, and 250 mg L-1. Ventilatory rate (VR) and transport for 8 h with 0, 10, and 15 mg L-1 of each essential oil were evaluated in juveniles II. The major components found in EOLS and EOCC were carvacrol (44.50%) and α-citral (73.56%), respectively. The best sedation and anesthesia times for both essential oils were obtained with 10 and 25 mg L-1 and 200 and 250 mg L-1 for juveniles I and II, respectively. Fish sedated with EOLS had lower VR values than the other treatments. Blood glucose levels were higher in ornamental fish transported with 10 and 15 mg EOLS L-1 and 15 mg EOCC L-1. Hepatic glycogen values were higher in the control group. In general, fish transported with 10 mg EOLS L-1 showed fewer gill histological alterations than other transported fish. When the type of lesion was evaluated, the highest gill alterations occurred in fish transported with EOCC. In conclusion, 10 mg EOLS L-1 could be used to transport of juveniles II because although this concentration increased blood glucose levels, it decreased the VR and muscle glycogen levels and caused only mild alterations to the gills.

Water pH and hardness alter ATPases and oxidative stress in the gills and kidney of pacu ( Piaractus mesopotamicus )

This study aimed to assess the effects of low and high water hardness in interaction with different water pH in pacu (Piaractus mesopotamicus). Pacu juveniles were subjected to low (50 mg CaCO3 L-1 - LWH) or high water hardness (120 mg CaCO3 L-1 - HWH) at water pH of 5.5 (acidic), 7.5 (circumneutral) or 9.0 (alkaline) for 15 days. Gills and kidneys were collected (days 1, 5 and 15). Gill Na+/K+-ATPase (NKA) and vacuolar-type H+-ATPase (V-ATPase) activities were higher in alkaline pH with HWH on day 1. Gill and kidney NKA and V-ATPase activities were higher in acidic pH with LWH on day 15. Gill NKA activity of pacus under alkaline pH with LWH was higher than those exposed to HWH. Reduced antioxidant capacity in the gills and kidney and enhanced thiobarbituric acid reactive substances (TBARS) levels were demonstrated in fish exposed to acidic or alkaline pH, mainly with LWH. HWH increased glutathione-S-transferase (GST) activity and reduced TBARS levels in the gills and kidney. On day 15, GST activity was increased at acidic pH with LWH. In conclusion, circumneutral pH presents less oxidative stress and fewer variations in ATPases and HWH reduced deleterious effects in fish exposed to acidic or alkaline pH.(AU)

Este estudo objetivou analisar o efeito de baixa e alta dureza da água em interação com diferentes pH da água em pacu (Piaractus mesopotamicus). Juvenis de pacu foram submetidos a baixa (50 mg CaCO3 L-1 - BDA) ou alta dureza da água (120 mg CaCO3 L-1 - ADA) em pH da água de 5.5 ácido), 7.5 (circum-neutro) ou 9.0 (alcalino) por 15 dias. Foram coletados brânquias e rim (dias 1, 5 e 15). Atividade de Na+/K+-ATPase (NKA) e H+-ATPase do tipo vacuolar (V-ATPase) branquial foram maiores em pH alcalino com ADA no dia 1. Atividade de NKA e V-ATPase branquial e renal foram maiores em pH ácido com BDA no dia 15. Atividade de NKA branquial de pacus submetidos a pH alcalino com BDA foi maior que aqueles expostos para ADA. Em peixes expostos a pH ácido ou alcalino com BDA houve redução da capacidade antioxidante nas brânquias e rim e aumento dos níveis de "substâncias reativas ao ácido tiobarbitúrico" (TBARS). Em ADA aumentou a atividade da "glutationa-S-transferase" (GST) e reduziu níveis de TBARS nas brânquias e rim. No dia 15, a atividade da GST foi maior em pH ácido com BDA. Em conclusão, pH circum-neutro apresentou menor estresse oxidativo e poucas variações na atividade de ATPases e ADA reduziu efeitos deletérios em peixes expostos a pH ácido ou alcalino.(AU)

Growth and biochemical variables in Amazon catfish ( Pseudoplatystoma reticulatum ♀ x Leiarius marmoratus ♂) under different water pH.

Although fish may live in different aquatic environments, variations in the water quality parameters, mainly pH, may have a substantial impact in their development and welfare. The objective of this study was to test the effect of different pH levels on the growth performance and biochemical variables in Amazon catfish juveniles (Pseudoplatystoma reticulatum x Leiarius marmoratus). Fish were subjected to four different water pH levels (4.56, 6.0, 7.24, and 8.90) for 40 days. The total ammonia and alkalinity were higher and lower, respectively, in the treatments with water pHs 4.56 and 6.00 than at the other water pH levels. The un-ionized ammonia was higher at water pH 8.90 than at the other water pH levels. Amazon catfish exposed to water pH 4.56 presented specific growth rate and weight gain significantly higher than other water pH values. In general, fish under exposure to water pH 8.90 presented lower growth performance than other water pH values. Biochemical changes were recorded at all water pH. In conclusion, water pH 4.56 is recommended for an Amazon catfish production system, since fish presented higher growth and water quality variables were kept within adequate limits for aquaculture.

Efficiency of essential oils of Ocimum basilicum and Cymbopogum flexuosus in the sedation and anaesthesia of Nile tilapia juveniles

ABSTRACT This study aimed to verify the sedative and anaesthetic effect of the essential oils of basil (Ocimum basilicum) (EOOB) and lemongrass (Cymbopogum flexuosus) (EOCF) in Nile tilapia juveniles. The fish were transferred to aquaria containing different concentrations of each essential oil: 10, 25, 50, 100, 200, 400 and 600 μL L-1. The time of sedation ranged from 7 to 31 seconds and the recommended concentration was 10 or 25 μL L-1 for both essential oils. The best times for anaesthesia and recovery were found for the concentrations of 400 μL L-1 for EOOB (135.2 and 199.1 seconds, respectively) and 600 μL L-1 for EOCF (327.1 and 374.8 seconds, respectively). In conclusion, we recommend the use of EOOB and EOCF for the sedation and anaesthesia of Nile tilapia at concentrations of 10-25 (for both), 400 and 600 μL L-1, respectively.

Antimicrobial and synergistic activity of essential oils of Aloysia triphylla and Lippia alba against Aeromonas spp.

The objective of this study was to identify and quantify the chemical constituents, as well as the antimicrobial, antibiofilm and synergistic activity with florfenicol of essential oils of Aloysia triphylla (EOAT) and Lippia alba (EOLA) against Aeromonas spp. The antimicrobial activity of EOAT and EOLA was verified by the minimum bactericidal concentration (MBC) and the action against biofilm forming and consolidated biofilm. The synergistic activity of EOAT and EOLA with florfenicol was performed by the checkerboard technique. The main components of EOAT were α-citral (39.91%), E-carveol (25.36%) and limonene (21.52%), while that of EOLA was linalool (81.64%). Aeromonas spp. isolates showed sensitivity to both essential oils with MBC between 195.3 and 3125.0 µL/mL. Two isolates were classified as non-producing, three as moderate and 16 as weak biofilm producers. The EOAT and EOLA interfered in the biofilm formation, from moderate to weak producers, but did not cause any interference in the consolidated biofilm. The EOAT and EOLA combined with florfenicol showed synergistic effect and reduced MBC. The EOAT and EOLA have potential for application as antimicrobial agents, as they interfere in the initial formation of biofilm and when combined with florfenicol, present a synergic effect with a reduction in the minimum dose of the antibiotic.

Efficiency of essential oils of Ocimum basilicum and Cymbopogum flexuosus in the sedation and anaesthesia of Nile tilapia juveniles.

This study aimed to verify the sedative and anaesthetic effect of the essential oils of basil (Ocimum basilicum) (EOOB) and lemongrass (Cymbopogum flexuosus) (EOCF) in Nile tilapia juveniles. The fish were transferred to aquaria containing different concentrations of each essential oil: 10, 25, 50, 100, 200, 400 and 600 µL L-1. The time of sedation ranged from 7 to 31 seconds and the recommended concentration was 10 or 25 µL L-1 for both essential oils. The best times for anaesthesia and recovery were found for the concentrations of 400 µL L-1 for EOOB (135.2 and 199.1 seconds, respectively) and 600 µL L-1 for EOCF (327.1 and 374.8 seconds, respectively). In conclusion, we recommend the use of EOOB and EOCF for the sedation and anaesthesia of Nile tilapia at concentrations of 10-25 (for both), 400 and 600 µL L-1, respectively.

Essential oil of Lippia alba in the transport of Nile tilapia / Óleo essencial de Lippia alba no transporte de tilápia-do-Nilo

ABSTRACT: This study aimed to examine the action of the essential oil of Lippia alba (EOLA) in the stress response for transport of Nile tilapia Oreochromis niloticus . The fish were transported into three treatments (in triplicate): control, 10 and 20 µL L-1 EOLA, with loading density of 15 fish/plastic bags for 8h. Plasma glucose levels were significantly decreased in fish exposed to 20µL L-1 EOLA in comparison with the control group and fish exposed to 10µL L-1 EOLA, but the plasma cortisol, lactate and paraoxonase levels were similar. Un-ionized ammonia and ventilatory rate demonstrated a significant reduction in the treatments with the use of EOLA. In conclusion the use of 20µL L-1 EOLA is indicated for Nile tilapia transport.

RESUMO: O estudo objetivou verificar a ação do óleo essencial de Lippia alba (EOLA) na resposta de estresse para o transporte de tilápia-do-Nilo Oreochromis niloticus . Os peixes foram transportados por 8h sob três tratamentos (triplicata): controle, 10 e 20µL L-1 EOLA. Níveis plasmáticos de glicose foram significativamente menores em peixes expostos a 20µL L-1 de EOLA, em relação com o grupo controle e os peixes expostos a 10µL L-1 de EOLA, mas, cortisol, lactato e paraoxonase plasmáticos foram similares. Amônia não-ionizada e taxa de ventilação demonstraram redução significativa nos tratamentos com EOLA. Conclui-se que o uso de 20µL L-1 de EOLA é indicado para o transporte de tilápia-do-Nilo.

Bioassessment using benthic macroinvertebrates of the water quality in the Tigreiro river, Jacuí Basin / Bioavaliação por macroinvertebrados bentônicos da qualidade da água no rio Tigreiro, Bacia do Jacuí

This study aimed to evaluate the water quality in the Tigreiro river, Jacuí river Basin, using different approaches. Benthic macroinvertebrates were sampled in July 2010 (winter) and February 2011 (summer) at five sites. In this study were analyzed: microbiological, physical and chemical variables, benthic macroinvertebrates richness and diversity, rapid ecological assessment protocol and benthic biotic indices (% EPT, BMWP'-IAP, ASPT, SOMI). A total of 5,852 individuals were collected belonging to 31 taxa of three Phyla: Annelida, Mollusca and Arthropoda. Chironomidae was the most abundant taxon (63.70%). A reduction in richness, diversity H' and evenness J' was observed from the initial stretches to the end stretches of Tigreiro river. The use of different approaches showed that sites in the rural area were less altered. The Tigreiro river was strongly impacted, mainly due to discharge of domestic effluents in the urban area, and the combination of different metrics was useful to detect impacted sites and the consequence for the water quality.

O objetivo deste estudo foi avaliar a qualidade de água do rio Tigreiro, bacia do rio Jacuí, pelo uso de diferentes abordagens. Macroinvertebrados bentônicos foram coletados em julho/2010 (inverno) e fevereiro/2011 (verão) em cinco pontos. Neste estudo foram analisados: variáveis microbiológicas, físicas e químicas, riqueza e diversidade de macroinvertebrados bentônicos, protocolo de avaliação ambiental rápida e índices bióticos de bentos (% EPT, BMWP'-IAP, ASPT, SOMI). Foram coletados 5.852 indivíduos pertencentes a 31 taxa de três Filos: Annelida, Mollusca e Arthropoda. Chironomidae foi o taxon dominante (63,70%). A redução de riqueza, diversidade H' e uniformidade J' ocorreram da porção inicial em direção à porção final do rio Tigreiro. O uso das diferentes abordagens mostrou que os pontos da área rural foram menos modificados. O rio Tigreiro apresentou-se fortemente impactado, principalmente pela descarga de esgotos domésticos na área urbana e o uso de diferentes métricas foi útil para detectar locais impactados e suas consequências para a qualidade de água.

Variação sazonal e diversidade de peixes do rio Cambará, Bacia do rio Uruguai / Seasonal variation and diversity of fishes of the Cambará river, Uruguay Basin

O objetivo deste estudo foi analisar a ictiofauna do rio Cambará, Bacia do rio Uruguai, bem como as dimensões corporais de seus representantes. O trabalho foi realizado em dois trechos do rio Cambará (2ª ordem) em Cruz Alta/RS. Para a realização da pesquisa foram identificados exemplares capturados em maio, setembro e novembro de 2009 e fevereiro de 2010. Utilizaram-se redes de espera, que permaneceram expostas por 24 horas, sendo revisadas a cada oito horas (1; 9 e 17 horas). Além das malhas de espera, também se utilizou rede de arrasto (malha 1,0 mm) e varas de pesca. Os peixes coletados foram catalogados e fixados em formol a 10,0% e depois conservados em álcool 70,0%. Ao todo, identificaram-se 420 indivíduos, pertencentes a 26 espécies distribuídas em oito famílias. As espécies classificaram-se em: constantes (23,08%), acessórias (42,31%) e acidentais (34,61%). As famílias Loricariidae (nove espécies e 156 indivíduos) e Characidae (sete espécies e 136 indivíduos) foram as mais abundantes. Entre os indivíduos coletados destacam-se como mais abundantes: Hemiancistrus fuliginosus (89), Astyanax eigenmanniorum (50) e Rhamdia quelen (44). Registraram-se uma espécie de grande porte (Hoplias lacerdae, com 164,92 g de peso total e 23,40 cm de comprimento total), cinco espécies de médio porte (98,55-164,92 g de peso total e 19,56-21,50 cm de comprimento total) e 20 espécies de pequeno porte (inferiores a 57,79 g de peso total e 17,38 cm de comprimento total). A diversidade coletada apresentou-se mais elevada nos meses mais quentes, principalmente entre 1 e 9 horas. A curva do coletor demonstrou que ainda existem espécies de peixes a serem coletadas no rio Cambará. Conclui-se que apesar da existência de impactos ambientais nos trechos de estudo, o mesmo demonstrou diversidade e riqueza satisfatórias, influenciados por fatores como heterogeneidade de habitats e oferta de material alóctone, bem como fatores intrínsecos (atividade e reprodução) das espécies presentes.

The aim of this study was to analyze the ictiofaun of Cambará River, Uruguay Basin, as well as the body dimensions of the organisms. The work was accomplished in two stretches of Cambará 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 Cambará 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.

Low water hardness and pH affect growth and survival of silver catfish juveniles / Baixa dureza da água e pH afetam o crescimento e a sobrevivência de juvenis de jundiá

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.

O objetivo deste estudo foi investigar os efeitos da exposição em baixas durezas da água (0; 25 e 50mg CaCO3 L-1) na faixa de pH 6,0-8,0 no crescimento e na sobrevivência de juvenis de jundiás (Rhamdia quelen). Os juvenis foram expostos aos tratamentos durante 32 dias. Os indivíduos mantidos em dureza zero da água apresentaram maior mortalidade em pH 7,0 e 8,0 do que aqueles submetidos aos outros tratamentos. O peso dos juvenis expostos ao pH 6,0 com zero dureza da água foram significativamente maiores do que aqueles mantidos na mesma dureza e em outras faixas de pH. A sobrevivência e o crescimento dos indivíduos expostos em 25 e 50mg CaCO3L-1 não foi afetado na faixa de pH 6,0-8,0. Portanto, a melhor dureza da água para o crescimento e de juvenis de jundiá é 25-50mg CaCO3 L-1 e em baixa dureza da água (próxima a zero) o pH deve ser reduzido.

Anesthesia of silver catfish with eugenol: time of induction, cortisol response and sensory analysis of fillet / Anestesia de jundiás com eugenol: tempo de indução, resposta ao cortisol e análise sensorial do filé

The aim of this study was to identify the time of anesthetic induction and recovery of silver catfish (Rhamdia quelen) exposed to eugenol. It was also determined the efficacy of the anesthetic as a stress reducing agent and performed a sensory analysis of the fillets from fish exposed to this substance. The silver catfish were exposed to air for 1min to carry out biometry, and blood was collected at 0, 1 and 4 hours later. Eugenol can be used in the range of 20-50mg L-1 for anesthetic induction in silver catfish, and recovery time from anesthesia was not affected by eugenol concentration. The control group showed significantly higher cortisol levels 4 hours after biometry than at time zero. Fish anesthetized with eugenol (50mg L-1) presented significantly lower plasma cortisol levels than control fish at the same time. These data indicate that eugenol inhibits the rise of cortisol in the blood. The sensory analysis test demonstrated that eugenol modifies the flavor of the fillet and therefore is contra-indicated for anesthetization of silver catfish that are intended for human consumption.

O objetivo deste estudo foi identificar o tempo de indução e recuperação anestésica de jundiás (Rhamdia quelen) expostos ao eugenol, bem como a eficácia desse anestésico na inibição do estresse e realizar análise sensorial dos filés dos peixes expostos a essa substância. Os jundiás foram expostos ao ar por um minuto para realização 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 indução da anestesia em jundiás, e o tempo de recuperação da anestesia não foi afetado pela concentração do eugenol. O grupo de controle mostrou níveis significativamente mais elevados do cortisol quatro horas após a biometria que no tempo zero. Os peixes anestesiados com eugenol (50mg L-1) apresentaram níveis significativamente mais baixos do cortisol plasmático 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 filés e consequentemente é contra-indicado para a anestesia do jundiá quando o filé for destinado ao consumo humano.

Uma importante revisão sobre o impacto de agroquímicos da cultura de arroz em peixes / A revision about impact of agrochemicals used in the rice field in fishes

Na lavoura arrozeira, o uso de agroquímicos no controle de plantas daninhas e insetos é recomendado para garantir maior produtividade. Entretanto, sua utilização pode acarretar uma série de efeitos em organismos não alvos, como os peixes. Deste modo, esta revisão tem como objetivo analisar os dados existentes sobre os efeitos dos agroquímicos utilizados no cultivo de arroz em peixes, de modo a propor estratégias que minimizem seu impacto. Existe grande variação entre os agroquímicos testados quanto à toxicidade, sendo a determinação da concentração letal mediana em 96 horas apenas uma estimativa inicial para estudos adicionais, uma vez que para muitos deles concentrações inferiores podem provocar alterações bioquímicas nos tecidos dos peixes, as quais se mostram mais efetivas como biomarcadores. Para minimizar o impacto dos agroquímicos deve-se utilizar sempre a dose mínima recomendada, e manter estática a lâmina de água do cultivo por um período mínimo de duas semanas após a aplicação, de modo que o princípio ativo seja degradado, reduzindo a toxicidade. Além disso, o manejo integrado de pragas é recomendando, bem como a rizipiscicultura, a qual evita a utilização dos agroquímicos e em alguns casos pode promover um rendimento semelhante.

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.

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

Fishes that live in the Amazonian environment may be exposed to several kinds of waters: "black waters", containing high dissolved organic carbon and acidic pH, "white waters", with ten fold higher Ca2+ concentrations than black waters and neutral pH, and "clear waters", with two fold higher Ca2+ concentrations than black waters and also neutral pH. Therefore, the aim of the present study was to analyze Ca2+ fluxes in the facultative air-breather Hoplosternum littorale (tamoatá) exposed to different Amazonian waters. Fishes were acclimated in well water (similar to clear water) and later placed in individual chambers for Ca2+ fluxes measurements. After 4 h, water from the chambers was replaced by a different type of water. Transfer of tamoatás to ion-poor black or acidic black water resulted in net Ca2+ loss only in the first 2 h of experiment. However, transfer from black or acidic black water to white water led to only net Ca2+ influxes. The results obtained allowed us to conclude that transfer of tamoatás to ion-poor waters (black and acidic black water) led to transient net Ca2+ loss, while the amount of Ca2+ in the ion-rich white water seems adequate to prevent Ca2+ loss after transfer. Therefore, transfer of tamoatás between these Amazonian waters does not seem to result in serious Ca2+ disturbance.(AU)

Os peixes que vivem na Amazônia são expostos a vários tipos de água: águas pretas, contendo grande quantidade de carbono orgânico dissolvido, águas brancas, com concentração de Ca2+ dez vezes maior que as águas pretas e pH neutro, e águas claras, com concentração de Ca2+ duas vezes maior que as águas pretas e pH também neutro. Dessa forma, o objetivo deste trabalho foi analisar o fluxo de Ca2+ no peixe de respiração aérea facultativa Hoplosternum littorale (tamoatá) exposto a diferentes tipos de águas amazônicas. Os peixes foram aclimatados em água de poço artesiano (semelhante à água clara) e depois colocados individualmente em câmaras para medir o fluxo de Ca2+. Após 4 h, a água das câmaras foi trocada por um tipo diferente de água. A transferência do tamoatá das águas pobres em íons água preta e preta ácida ou da água branca, rica em íons, para as águas preta e preta ácida, pobres em íons, resulta em uma perda de Ca2+ apenas nas duas primeiras horas de experimento. Entretanto, a transferência da água preta e preta ácida, para a água branca resulta em um influxo de Ca2+. Os resultados obtidos nos permitem concluir que a transferência do tamoatá para as águas preta e preta ácida, pobres em íons, leva a uma temporária perda de Ca2+, e a quantidade de Ca2+ na água branca, rica em íons, é adequada para prevenir sua perda após a transferência. Sendo assim, a transferência do tamoatá entre as águas estudadas não resulta em sérios distúrbios no Ca2+.(AU)

Ictiofauna da microbacia do Rio Jaguari, Juaguari/RS, Brasil / Ichthyofauna of the Jaguari river microbasin, Jaguari /RS, Brazil

A microbacia do rio Jaguari pertence à Bacia Hidrográfica do rio Uruguai e tem sua foz na margem superior do rio Ibicuí. Este trabalho teve o objetivo de identificar a Ictiofauna existente em um trecho da microbacia do rio Jaguari, em Jaguari-RS. Para a realização da pesquisa foram realizadas identificações de exemplares capturados nas quatro estações do ano, através do uso de redes de espera das seguintes malhas (medidas em cm entre nós adjacentes): 1,0; 1,5; 2,0; 2,5; 3,0; 4,0; 5,0; 6,0; e 7,0. As redes de espera permaneceram na água por 24 horas, sendo revisadas a cada seis horas, sempre nos mesmos horários (06:00; 12:00; 18:00 e 24:00 horas). Os peixes coletados, após serem identificados, foram numerados e, logo após, fixados em formol a 4,0 por cento e depois conservados em álcool 70,0 por cento. Foram identificados um total de 572 indivíduos, distribuídos em 14 famílias e 26 espécies. Na primavera ocorreu a maior captura, com 156 indivíduos, distribuídos em 15 espécies; no verão ocorreu a maior riqueza, com 146 indivíduos distribuídos em 19 espécies; já no outono e inverno ocorreu uma captura de 135 indivíduos para ambas as estações, com 16 e 12 espécies, respectivamente. A espécie mais abundante, com 291 exemplares, foi Apareiodon affinis, sendo que Hemiancistrus fuliginosos (75), Hypostomus commersoni (50) e Steindachnerina brevipina (41) também tiveram alta representatividade.

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 Ibicuí. 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 percent and later in alcohol 70.0 percent. 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.

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), traíra (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.

Neste estudo verificaram-se dados de temperaturas de água coletados pela CORSAN-RS de 1996 a 2004, em várias cidades do estado do Rio Grande Sul, sul do Brasil, e analisou-se a possibilidade de criação das principais espécies de peixe cultivadas no Brasil. A temperatura da água de 1996 a 2004 foi de 16 a 28ºC no verão, de 17 a 25ºC no outono, 14 a 17ºC (chegando a 9ºC nos meses mais frios) no inverno e 14 a 21ºC na primavera. Espécies nativas deste estado, como o jundiá (Rhamdia quelen), traíra (Hoplias malabaricus), dourado (Salminus brasiliensis), pintado (Pimelodus maculatus), assim como as carpas (família Cyprinidae), são resistentes às baixas temperaturas do inverno. Estas espécies apresentam uma menor taxa de crescimento nos meses mais frios (inverno/primavera), mas um bom desenvolvimento em meses mais quentes (verão/outono), alcançando um desempenho satisfatório durante o ano. Nos períodos de frios mais intensos pode ocorrer uma intensa mortalidade de algumas espécies introduzidas, como o surubim da Bacia Amazônica (Pseudoplatystoma sp.), pirapitinga (Piaractus brachypomus), pirarucu (Arapaimas gigas), pacu (Piaractus mesopotamicus), tambaqui (Colossoma macropomum) e tilápia nilótica (Oreochromis niloticus). Além disso, como a maioria das espécies tropicais apresenta sua faixa térmica para crescimento e reprodução entre 20 a 28ºC, algumas espécies podem ter um baixo desenvolvimento também no outono. Portanto, a temperatura da água deste estado deve ser considerada na escolha das espécies de peixes a serem cultivadas.