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Ectoparasitas de tilápias-do-Nilo (Oreochromis niloticus) criadas em tanques-rede em um reservatório de usina hidrelétrica no Brasil AbstractFor this study, we performed a parasitological analysis of cage-cultured Nile tilapia (Oreochromis niloticus) from the Água Vermelha Reservoir, Southeastern Brazil, and verified relationships with limnological data, seasonality, and fish growth phase. From March 2010 to March 2011, sixty-three specimens of O. niloticus in three growth phases (i.e., initial, intermediate, and final) were collected. All fish specimens were infested with at least one ectoparasite species (prevalence = 100%). Five species of protozoans (Trichodina compacta, Trichodina magna, Ichthyophthirius multifiliis, Piscinoodinium pillulare, and Epistylis sp.) and five species of monogenoids (Cichlidogyrus halli, Cichlidogyrus thurstonae, Cichlidogyrus sp. 1, Scutogyrus longicornis, and Gyrodactylus sp.) were observed. The abundance of Trichodina spp. and the prevalence of Epistylis sp. were higher in the dry season, and the prevalence of C. halli was higher in the rainy season. For the majority of ectoparasites found in this study, fish in the intermediate and final phases had higher parasitism rates than those in the initial phase. The data presented may help fish farmers to understand the parasite dynamics of the fish species studied in cage-farming systems.Keywords: Fish farming, health, water quality, monogenoid, Trichodina spp., Ichthyophthirius multifiliis. ResumoO presente estudo teve como objetivo realizar análise parasitológica de tilápias-do-Nilo, (Oreochromis niloticus) criadas em tanques-rede no Reservatório de Água Vermelha, Sudeste do Brasil, bem como verificar suas inter-relações com as características limnológicas, sazonalidade e fase de criação. Durante o período de março de 2010 a março de 2011, espécimes de O. niloticus, pertencentes a três fases de criação (inicial, intermediária e final), foram colhidos, totalizando 63 indivíduos. Todos os peixes estavam infestados por pelo menos uma espécie de ectoparasita (prevalência = 100%). Foi observada a ocorrência de cinco espécies de protozoários (Trichodina compacta, Trichodina magna, Ichthyophthirius multifiliis, Piscinoodinium pillulare e Epistylis sp.), assim como cinco espécies de monogenóides (Cichlidogyrus halli, Cichlidogyrus thurstonae, Cichlidogyrus sp. 1, Scutogyrus longicornis e Gyrodactylus sp.). A abundância de Trichodina spp. e prevalência de Epistylis sp. foram maiores no período seco, e a prevalência de C. halli foi maior no período chuvoso. Para a maioria dos ectoparasitas encontrados neste estudo, os peixes pertencentes às fases intermediária e final apresentaram maiores taxas de parasitismo do que aqueles pertencentes à fase inicial. Os dados apresentados neste estudo podem ser de grande importância para piscicultores, de forma a auxiliá-los no conhecimento da dinâmica dos parasitas da espécie de peixe estudada em sistemas de tanques-rede.Palavras-chave: Piscicultura, sanidade, qualidade da água, monogenóide, Trichodina s...

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Considering that most of the energy supply in Brazil is derived from hydroelectric sources, the government has been strongly encouraging cage farming in federal water bodies. The government limited the aquaculture parks in hydroelectric reservoir to only 1% of its total area and, inside the parks, a ratio of 1:8 referring to the park and organic load dilution area. However, no objective evaluations proved that limit is suitable, and the absence of a methodology to evaluate this impact is a considerable problem. The aim of this study was to evaluate the Nile tilapia cage farming sustainability in a hydroelectric reservoir in Brazil using an emergy assessment and to simulate management techniques and public policies that contribute to the sustainability of this farming system. The results of the emergy assessment indicate that this production model has low renewability, is inefficient (mostly due to feeding), does not use local resources and presents high environmental impact. Therefore, we have analyzed three scenarios, in which reducing the inputs of non-renewable resources and enhancing environmental inputs were considered. Reducing the stocking density from 100 to 20 kg/m 3 in the initial farming stage and enhancing the dilution area from 1:8 to 1:100, referring to the cage and organic load dilution area, makes the current production system a sustainable model based on the use of natural renewable resources.

Infecções parasitárias de AbstractThis study evaluated the occurrence of parasitic infections in the "pacu" fish Piaractus mesopotamicus and the "patinga" hybrid (P. mesopotamicus x Piaractus brachypomus) in the northwest of São Paulo State, Brazil. Fish from the following three fish farms were evaluated every two months: A, a hatchery and larviculture farm (n = 16 pacu / n = 19 patinga), B, a growout farm (n = 35 patinga) and C, a fee-fishing property (n = 28 pacu / n = 7 patinga). Thirty-five fish from each property were collected from February 2010 to February 2011 and subjected to parasitological analysis. The parasites found were the following: Mymarothecium viatorum, Anacanthorus penilabiatus, Notozothecium janauachensis (Dactylogyridae, Monogenea), Trichodina spp., Ichthyophthirius multifiliis, Chilodonella sp. (Protozoa), Myxobolus spp., Henneguya spp. (Myxozoa), Rondonia rondoni, Contracaecum sp. (Nematoda), and Dolops carvalhoi (Crustacea). Of the fish examined, 62.9% from "A" and 100% from "B" and "C" were infested with at least one parasite species. Pacu fish (n = 44) showed a higher susceptibility to Anacanthorus penilabiatus infestations, whereas patinga (n = 61) were more susceptible to Mymarothecium viatorum (p < 0.05). Appropriate fish handling (nutrition, transport and storage), in conjunction with monitoring of water quality, can reduce the stress to which the farmed fish are exposed and is essential for pathogen control.Keywords: Handling, helminths, protozoans, storage control, water quality. ResumoEste estudo avaliou a ocorrência de infecções parasitárias em pacus Piaractus mesopotamicus e do híbrido patinga (P. mesopotamicus x P. brachypomus) procedentes da região Noroeste do Estado de São Paulo, Brasil. Peixes de três pisciculturas foram avaliados bimestralmente: A -Reprodução e Larvicultura (n = 16 pacus / n = 19 patingas), BEngorda n = 35 patingas), e C-Pesque-pague (n = 28 pacus / n = 7 patingas). Trinta e cinco peixes de cada propriedade (Crustacea). Dentre os peixes analisados, 62,9% de "A" e 100% de "B" e "C" estavam infectados/infestados por pelo menos uma espécie de parasita. Pacus (n = 44) apresentaram maior suscetibilidade a infestações por Anacanthorus penilabiatus, e patingas (n = 61), por Mymarothecium viatorum (p < 0.05). A profilaxia e cuidados durante o manejo (alimentação, transporte e estocagem), associados ao monitoramento da qualidade de água reduzem o estresse o qual os peixes cultivados estão submetidos, sendo medidas imprescindíveis para o controle de patógenos.Palavras-chave: Manejo, helmintos, protozoários, controle de estocagem, qualidade de água.

In land-based pond cultures, periphyton is considered to be a complementary food source for cultured fish. In cage aquaculture, studies on the use of periphyton are scarce and do not support the viability of periphyton-based cage culture. The aim of this study was to evaluate the potential of periphyton-based cage culture of Nile tilapia in a hydroelectric reservoir in Brazil at three stocking densities and two feeding regimes.Sex-reversed male Nile tilapia Oreochromis niloticus (46.56±2.53 g) were placed in 21 cages (6 m 3 -2 x 2 x 1.5 m each) with or without bamboo substrates for periphyton growth. A completely randomized design with three replicates per treatment was used to test the effect of substrate inclusion in the three stocking densities (80, 60, 40 kg of fish/m 3 ) associated with two feeding regimes (100% and 50% of daily ration). Three cages without bamboo substrates were included in the experimental design as control group (CTRL) (80 kg/m 3 and 100% of daily ration). The study demonstrates the efficiency of using substrates for Nile tilapia in cages in the reservoir. The presence of bamboo substrates improved the weight gain of fish but reduced the carrying capacity of the cage at the highest density. The concentration of dissolved oxygen in the cages was improved by the presence of substrate between 50 and 140 days of the trial and reduced after 155 days of culture. The inclusion of bamboo substrates inside the cages allows producing up to 52 kg/m3 of Nile tilapia using 32% less diet in a period almost 20% shorter than in the CTRL group. If farmers prefer to produce 80 kg/m3, they can use 30 % less diet but the production period would be 20% longer.