Environmental color affects Nile tilapia reproduction

We investigated the effects of environmental color on the reproductive behavior of Nile tilapia, Oreochromis niloticus. Two environmental colors were tested by covering the aquarium (60 x 60 x 40 cm) with white (12 groups) or blue (13 groups) cellophane and observing reproductive behavior in groups of 2 males (10.27 ± 0.45 cm) and 3 females (10.78 ± 0.45 cm) each. After assignment to the respective environmental color (similar luminosity = 100 to 120 Lux), the animals were observed until reproduction (identified by eggs in the female's mouth) or up to 10 days after the first nest building. Photoperiod was from 6:00 h to 18:00 h every day. Food was offered in excess once a day and water quality was similar among aquaria. Daily observations were made at 8:00, 11:00, 14:00 and 17:00 h regarding: a) latency to the first nest, b) number of nests, c) gravel weight removed (the male excavates the nest in the bottom of the aquarium), d) nest area, and e) mouthbrooding incubation (indication of reproduction). The proportion of reproducing fish was significantly higher (6 of 13) in the group exposed to the blue color compared the group exposed to the white color (1 of 12; Goodman's test of proportions). Moreover, males under blue light removed significantly larger masses of gravel (blue = 310.70 ± 343.50 g > white = 130.38 ± 102.70 g; P = 0.01) and constructed wider nests (blue = 207.93 ± 207.80 cm² > white = 97.68 ± 70.64 cm²; P = 0.03) than the control (white). The other parameters did not differ significantly between light conditions. We concluded that reproduction in the presence of blue light was more frequent and intense than in the presence of white light.

Práticas de cura místico-religiosas, psicoterapia e subjetividade contemporânea

Nous avons analysé les résultats d'une recherché sur les pratiques de guérison mystico-religieuses (chez les Églises Évangéliques et Catholique Renovée, et chez l'Oumbanda). Ainsi que leur comparaison avec le traitement fourni, chez les Ambulatoires de Santé Mentale publiques, aux individus se plaignant de souffrance psychique. L'analyse statistique a révélé que les pratiques de guérison mystico-religieuses sont efficaces à la solution des problèmes de ceux qui les ont cherché, en surmontant, dans le court délai, l'efficacité obtenue par les pratiques ambulatoriales. Un des principaux moyens d'efficacité des pratiques de guérison mystico-religieuses consiste dans l'offre de sens de diverses nuances, d'où se ressort le sens radical de teneur imaginaire, qui implique en des adhésions institutionelles du type fanatique ou ritualistique en bonne partie des cas. Les pratiques de guérison mystico-religieuses semblent fonctioner comme des orthopédies des maladies de l'individualisme contemporain, en réinstallant, par des moyens syntoniques, quelque fonctionalité de la catégorie individu. Comme suite de l'analyse, nous arrivons à l'hypothèse sur l'existence d'une Culture du Mysticisme en état avancé de formation dans le contexte brésilien, comme conséquence des caractéristiques culturelles et des effets de la perturbation des rapports du sujet avec le domaine du symbolique, dans les sociétés de consommation mondialisées à exclusion sociale accentuée et affectées par une importante crise de sens, conséquence de l'ébranlement des idéaux les plus basilaires du libéralisme.

Desempenho de tricogaster (Trichogaster trichopterus) submetido a diferentes níveis de arraçoamento e densidades de estocagem

O potencial genético para o crescimento de qualquer espécie animal depende das condições ambientais em que são cultivados, como competição por espaço, alimentos e oxigênio. O presente experimento foi conduzido com o objetivo de avaliar o desempenho produtivo de alevinos de tricogaster (Trichogaster trichopterus), uma espécie de peixe ornamental, submetidos a diferentes densidades de estocagem e índices alimentares. Os peixes (com peso médio de 0,56 g ± 0,09 e 0,96 g ± 0,13) foram divididos em dois blocos, submetidos às densidades de 5, 10 e 15 peixes/aquário e alimentados a taxas de 3, 6 e 9% do peso vivo/dia. Os peixes foram alimentados, uma vez ao dia, com ração comercial moída e mantidos em aquários (com capacidade para 100 L) dotados de filtro biológico e aeração, com renovação parcial da água. Os parâmetros físico-químicos da água mantiveram-se dentro da faixa de conforto para a espécie, com diminuição do pH e da condutividade no final do período experimental, para a maior densidade (15 peixes/aquário) e índice alimentar mais elevado (9% p.v./dia). A taxa de arraçoamento afetou significativamente o comprimento final, peso final, ganho de peso, a taxa de crescimento específico e o fator de condição. Os peixes alimentados à base de 9% p.v./dia apresentaram os melhores resultados. Para as diferentes densidades de estocagem, apenas o fator de condição apresentou diferença significativa, com os melhores resultados para os peixes cultivados à densidade de 10 peixes/aquário, em relação aos cultivados à densidade de 15 peixes/aquário. Não foram observadas interações significativas entre os índices alimentares e as densidades de estocagem.

Farinha de resíduos da filetagem de tilápias na alimentação de tilápia-do-nilo (Oreochromis niloticus) na fase de reversão sexual

Este trabalho foi realizado com o objetivo de avaliar a inclusão da farinha de resíduos da indústria de filetagem de tilápias (FT) na alimentação da tilápia-do-nilo na fase de reversão sexual. Foram utilizadas 375 larvas com dois a três dias de idade, distribuídas em 25 aquários com capacidade para 30 L, em delineamento inteiramente casualisado, com cinco tratamentos e cinco repetições, sendo a unidade experimental constituída por um aquário com 15 larvas. Foram elaboradas cinco rações isoprotéicas e isoenergéticas com 38,6% de proteína digestível e 3.800 kcal de ED/kg, com níveis de 0, 5, 10, 15 e 20% de inclusão de FT. Os valores de temperatura, oxigênio dissolvido, pH e condutividade elétrica da água dos aquários durante o período experimental foram de 24,53 ± 1,60ºC; 4,81 ± 0,68 mg/L; 7,70 ± 0,25; e 175,97 ± 108,46 µS/cm, respectivamente. Ao final do experimento, não foram observadas diferenças no peso e comprimento final, no fator de condição, na sobrevivência e no índice de reversão sexual das larvas alimentadas com a FT. A inclusão de até 20% de FT em rações para tilápia do Nilo na fase de reversão sexual não causa prejuízo ao desempenho dos peixes.

Influência do formato do aquário na sobrevivência e no desenvolvimento de larvas de matrinxã Brycon cephalus (Osteichthyes, Characidae)

Neste experimento, utilizaram-se cinco aquários cilíndricos com relevo no fundo (em forma de anel) e cinco retangulares com fundo liso para estudo da influência do formato do aquário na sobrevivência e no desenvolvimento de larvas de matrinxã Brycon cephalus. Observou-se melhor eficiência dos aquários retangulares, confirmada pela maior sobrevivência e biomassa. Os valores de temperatura, pH, condutividade e oxigênio dissolvido foram similares entre os tipos de aquários, sugerindo que esses parâmetros não influenciaram os resultados. O relevo no fundo dos aquários cilíndricos afetou negativamente o cultivo de larvas de matrinxã, pela criação de zonas com pequena capacidade da água em suspender partículas, o que resultou em acúmulo de dejetos, predadores, competidores e alimento. Aquários retangulares com fundo liso são mais adequados ao cultivo de larvas de matrinxã, por promover melhor circulação da água.

Níveis de arraçoamento para juvenis de trairão (Hoplias lacerdae)

Com esta pesquisa buscou-se avaliar diferentes níveis de arraçoamento, em porcentagem de peso corporal (PC), para juvenis de trairão em início do período de engorda. Peixes com comprimento de 15,0 ± 1,0 cm e peso de 38,5 ± 8,2 g foram distribuídos em seis aquários com 250 litros de água cada, em densidade de cinco juvenis/aquário. Utilizou-se delineamento inteiramente casualisado com três tratamentos (níveis de arraçoamento diário: 2, 4 e 6% PC) e duas repetições. Os juvenis foram alimentados com ração comercial extrusada (42% PB), às 8 e 13 h. Ao final de 45 dias, avaliaram-se a sobrevivência, a conversão alimentar aparente e os ganhos em biomassa, peso diário e comprimento. Não houve diferença para sobrevivência e ganhos em biomassa, peso diário e comprimento. Houve diferença para a conversão alimentar aparente em função do manejo adotado. Os melhores resultados de desempenho foram encontrados nos peixes alimentados com níveis de 2 e 4% PC de ração por dia. Conclui-se que a melhor taxa de arraçoamento para juvenis de trairão é de 4% PC.

Dietary protein and energy requirements of juvenile freshwater angelfish

Avaliaram-se as exigências nutricionais de proteína e energia em juvenis de acará-bandeira (Pterophyllum scalare). Utilizou-se delineamento inteiramente casualizado, em esquema fatorial 3 × 2, com três níveis de proteína bruta (26, 30 e 34%), dois de energia digestível (3.100 e 3.300 kcal/kg de ração) e três repetições. Juvenis com peso médio de 2,33 ± 0,26 g foram distribuídos em aquários contendo 25 litros de água, temperatura controlada (26 ± 1ºC) e filtro biológico, na densidade de estocagem de seis animais por aquário. Os peixes foram alimentados à vontade às 9, 14 e 16h30. Na análise do desempenho produtivo, foram avaliados o peso final, o comprimento final, o ganho de peso, o consumo de ração, a conversão alimentar, a taxa de crescimento específico, a taxa de eficiência protéica e o fator de condição. As dietas contendo 26% PB proporcionaram maiores valores para taxa de eficiência protéica apenas em relação às dietas contendo 34% PB. As exigências nutricionais de proteína e energia em juvenis de acará-bandeira podem ser atendidas com dietas contendo 26% PB e 3.100 kcal ED/kg.

Chemical communication, aggression, and conspecific recognition in the fish Nile tilapia

The chemical modulation of agonistic behavior and conspecific recognition were tested in juveniles of the fish Nile tilapia, Oreochromis niloticus (L.). After a 7-day isolation period, the fish were grouped (four individuals per aquarium) for 7 days. Then fish of alpha and beta ranks (previously matched for similar size) were paired in a neutral territory for analysis of their agonistic interaction. Pairs composed of alpha and beta fish were established with either fish from the same group (familiar) or from two different groups (unfamiliar). The pairs were tested in contiguous compartments, either with water exchange between the compartments or in the absence of water exchange. In each condition the fish were separated by a transparent glass partition. Twelve pairs were tested in each experimental condition. Fish behavior was videotaped and the following variables were analyzed: (a) frequency of and time spent in agonistic patterns, (b) latency to start fighting, and (c) duration of swimming. Water exchange between compartments decreased agonistic interactions. This effect, however, was more pronounced in pairs of fish coming from the same group (in this case, subordinate fish spent less time in confrontations than dominant ones). We conclude that chemical communication decreases aggression in this species by (1) inducing an alarm reaction and (2) increasing conspecific recognition (thus stabilizing the dominance hierarchy). (C) 1997 Elsevier B.V.

EFFECT OF ASCORBIC-ACID DEFICIENCY ON THE GROWTH, GILL FILAMENT LESIONS AND BEHAVIOR OF PACU FRY (PIARACTUS-MESOPOTAMICUS HOLMBERG, 1887)

The effect of ascorbic acid deficiency was determined in Piaractus mesopotamicus Holmberg, 1887, fish (pacu) under laboratory conditions. A total of 120 fish with an average body weight of 8.64 +/- 1.62 g and measuring 6.15 +/- 0.33 cm in length at the beginning of the experiment were fed diets containing 0, 50, 100 or 200 mg palmitate-coated ascorbic acid/kg dry ration for a period of 24 weeks with measurements every 4 weeks. The experiment was conducted in 20 fiber-cement aquaria of 81-liter capacity. Each aquarium was supplied with dechlorinated water at a flow rate of 1 l/min. Water temperature was measured daily and pH, dissolved oxygen, alkalinity and water conductivity were determined weekly. A fully randomized experimental design was utilized, with 5 replicates of each treatment and 6 fish per aquarium. Ascorbic acid-supplemented fish presented significantly increased growth when compared to unsupplemented fish. Furthermore, unsupplemented fish presented a higher incidence of hyperplasia, hypertrophy and dysplasia of the bone cartilage of gill filaments. The gill lamellae of unsupplemented fish had twisted cartilage and an inflammatory infiltrate at the ends. Anorexia and increased handling stress were also observed in fish fed the unsupplemented diet. The present study suggests that 50 mg ascorbic acid/kg dry ration is sufficient to improve development of pacu fingerlings but the optimum level under aquarium conditions, determined by regression analysis, is 139 mg ascorbic acid/kg dry ration.

Digestibilidade Aparente e Efeito Macro-Microscópico em Tilápia do Nilo (Oreochromis niloticus) Arraçoadas com Torta de Dendê

To evaluate the nutritional value of palm kernel meal on the performance Nile tilapia (Oreochromis niloticus), five isonitrogenous (30% crude protein), isoenergetic (2800 kcal/kg of digestible energy), and isofibrous (10% crude fiber) diets, with increasing levels of palm kernel meal (0, 7, 14, 21, 28 and 35%). were ad libitum fed to fingerlings with initial body weight of 1.52g +/- 0.04, housed per 120 days in 35 aquarium of 60 liters with fingerlings each. The environmental culture condition were monitored during all experimental period. Statistical analyses of recorded data were performed through polynomial regression models. To determine the apparent digestibility, macroscopic analysis of viscera and microscopic analysis of intestine epithelium were performed. The obtained results indicated that the inclusion of palm kernel meal up to 35% Nile tilapia diets did not affects the apparent digestibility and did not induce any pathological effects on viscera and intestinal epithelium.

Influência da densidade de estocagem no desempenho produtivo do acará-bandeira (Pterophyllum scalare)

The present study aimed to evaluate the effects of three different stock densities (0.33; 0.67 e 1.00 fish L-1) on freshwater angelfish productive performance reared in aquarium. Fish were fed with commercial diets during 35 days in two diary meals. The experimental design was entirely randomized and for each density were used four replicates. Were evaluated physical-chemical water parameters: temperature, oxygen dissolved concentration and total ammonia concentration and growth performance parameters: weight gain, feed conversion, specific growth rate, final standard length, conduction factor and length uniformity. Results were submitted to variance analysis and means were compared by Tukey's test (alpha = 0.05), it was used the statistic program ESTAT 2.0. Mortality was not observed in any tested density. on physical-chemical water parameters, total ammonia level increased significantly with stock density increasing, but they did not showed clinical signs of ammonia toxicity. As there were no significant differences between treatments, stock density 1.00 fish L-1 is the most indicated because it allows higher production.

Intriguing evidence of translocations in Discus fish (Symphysodon, Cichlidae) and a report of the largest meiotic chromosomal chain observed in vertebrates

As part of a program to understand the genetics of Amazonian ornamental fish, classical cytogenetics was used to analyze Symphysodon aequifasciatus, S. discus and S. haraldi, popular and expensive aquarium fishes that are endemic to the Amazon basin. Mitotic analyses in Symphysodon have shown some odd patterns compared with other Neotropical cichlids. We have confirmed that Symphysodon species are characterized by chromosomal diversity and meiotic complexity despite the fact that species share the same diploid number 2n = 60. An intriguing meiotic chromosomal chain, with up to 20 elements during diplotene/diakinesis, was observed in S. aequifasciatus and S. haraldi, whereas S. discus only contains typical bivalent chromosomes. Such chromosomal chains with a high number of elements have not been observed in any other vertebrates. We showed that the meiotic chromosomal chain was not sex related. This observation is unusual and we propose that the origin of meiotic multiples in males and females is based on a series of translocations that involved heterochromatic regions after hybridization of ancestor wild Discus species. Heredity (2009) 102, 435-441; doi: 10.1038/hdy.2009.3; published online 25 February 2009

Influência do fotoperíodo no crescimento e sobrevivência de póslarvas de piracanjuba Brycon orbignyanus (Valenciennes, 1849) (Osteichthyes, Characidae)

This paper aims at studying the influence of photoperiod on the cultivation of Brycon orbignyanus (Valenciennes, 1849) (Osteichthyes, Characidae) post-larvae submitted to four treatments: 0L-24D (L=Light; D=Dark), 10 - L14D, 14L - 10D and 24L-0D, with 3 repetitions. Post-larvae measuring 7.8±0.7mm and weighting 3.5±0.8mg were distributed in 12 aquariums (10L), stocked with 12 post-larvae per aquarium. Fishes were fed daily with Artemia sp. nanplii, in 10 days experiment. A positive relationship between the survival rate (88.9±9.7%) observed in the treatment with 24 hours of luminosity, and the lowest (58.3±8.3%), in the treatment with 24 hours of darkness. No difference was showed (P>0.05) in the mean length and weight of the post-larvae, although there was greater heterogeneity among the post-larvae cultivated at the longer darkness period.

Energia digestível para larvas de tilápia-do-nilo (oreochromis niloticus) na fase de reversão sexual

This experiment was conducted to evaluate different levels of digestible energy on the performance of Nile tilapia larvae (Oreochromis niloticus) during the sexual reversion phase. Three hundred and seventy-five larvae with initial average length and weight of 21.0±4.0 mg and 1.19±0.72 cm, respectively, were allotted to 25 30L-aquarium. A completely randomized design with five treatments and five replicates was used. The aquarium with 15 larvae was the experimental unit. The diets were formulated to contain levels of 3,300, 3,525, 3,750, 3,975, and 4,200 kcal/kg of digestible energy and to be isoprotein (38.6% digestible protein). The animals were fed ad libitum five times a day. At the end of the experiment, the averages of weight (PF), survival rate (SO), condition factor (FC) and length (CF) were analyzed. Linear reduction of fishes PF and CF, as the dietary digestible energy levels increased, was observed. No differences on fish SO and FC of different treatments were observed. Deleterious effects on performance due to the increasing dietary digestible energy levels were noticed for Nile tilapia larvae during the sexual reversion.

Desenvolvimento de larvas de Steindachneridion sp. em diferentes condições de refúgio eluminosidade

The influence of luminosity and of the use of refuges on the initial development of Steindachneridion sp. Garavello (Siluriforme: Pimelodidae) larvae was evaluated. A thousand larvae 18.02 mm high and 62.2 mg weight were used in an entirely randomized design, with five treatments and four replicates, in 35 L-aquarium during 22 days. The treatments consisted on the following environments: darkness without refuges, clear with artificial refuge, darkness with artificial refuge, clear with natural refuge and clear without refuge. All larvae received the same feeding during the experiment. The best survival rates were found for darkness without refuges, clear with artificial refuge and clear without refuge, with 84, 76 and 70%, respectively. The best development was in darkness and without refuges. The treatment darkness with artificial refuge provided significant differences in relation to the other treatments as far as survival and weight are concerned, showing high heterogeneity for weight. Environment without refuges are the most appropriate for the larval development of this specie.