The banded cichlid (Herus severus) is an Amazonian species with potential as ornamental fish, however basic handlings as quantity and feeding frequency as well as stocking density in larviculture are still unknown in order to allow the rational production of this species in captivity. Then the objective was to evaluate the amount of food, feeding frequency and stocking density during the larviculture of Herus severus. Therefore, two experiments were conducted: the first assessed the food concentration (100, 150, 200, 250 and 300 Artemia larvae-1) and feed rate (2 or 4 meals day-1), and the second experiment evaluated different stocking densities (1, 5, 10, 15, 20 larvae L-1) with four replications each. Feeding of 250 nauplii larva day-1 distributed in four daily meals promoted the highest weight, length, specific growth rate, weight gain and survival. In the second experiment, reduction in growth was observed with increased in density due to lower concentrations of dissolved oxygen and elevated total ammonia from 5 larvae L-1. Thus, to promote the rational cultivation of the Banded cichlid larvae in captivity, the species should be reared at 5 larvae L-1 fed with 250nauplii distributed along 4 daily meals.
The study evaluated productive performance of larvae Nannostomus beckfordi submitted to feeding management (Experiment one) and different stock density (Experiment two) in captivity conditions. The first experiment evaluated feeding rate (100 and 200 nauplii of artemia larvae −1 day −1 ) and feeding frequency (2 and 4× per day). Second experiment evaluated different stock density (1, 5, 10, 20, 40 larvae per litre). At the end of 15 days, for both experiment, the survival and productive performance such as total length (TL), final weight (FW), specific development rate (SDR), specific growth rate (SGR), uniformity for weight (UW) uniformity for length (UL) and relative condition factor (Kr) was determined. For the main results, there is no significant difference to the rate and feeding frequency. The stock density has no significant difference for UW, Kr and survival. Nonetheless, a reduction in the TL, FW, SDR, SGR and FW with the increase in density (20 for 40 larvae per litre) was observed. Thus, for this species Nannostomus beckfordi during to initial stage using exogenous feeding, it is recommended 20 larvae per litre fed with 100 nauplii per larvae having two meals per day.
Intensive fish farming has resulted in an increased concern for disease outbreaks. Probiotic use is one of the strategies being developed to improve fish health and productivity. Measures of probiotic colonization, growth performance, haematological characteristics and parasite load were used to evaluate the effect of diets supplemented with Enterococcus faecium on growth and health of Arapaima gigas juveniles. A completely randomized design with four treatments (diet with E. faecium at 1 × 106 CFU/g and 1 × 108 CFU/g, control diet and diet with the culture medium MRS) and three replicates was used. Ninety‐six Arapaima juveniles were distributed in 12 cages fed with the specified diet for 68 days. Colonization of the intestinal tract by lactic acid bacteria reduced the total number of heterotrophic bacteria in fish fed with probiotics compared to controls. Fish fed a supplemented diet containing 1 × 108 CFU/g presented higher values of weight gain, survival and fish growth uniformity, and lower values of feed conversion ratio. The prevalence of Trichodina sp. could have affected the survival of fish in the control group. Reduction in parasite load and an increase in haematocrit, the number of erythrocytes, thrombocytes, neutrophils and monocytes were also observed in fish fed the diet containing 1 × 108 CFU/g. Enterococcus faecium presented a probiotic effect in A. gigas juveniles and can be recommended for use at a concentration of 1 × 108 CFU/g to modify the gut microbiota, improve growth performance and haematology and reduce parasitic load.
RESUMO Este trabalho teve como objetivo avaliar a fauna parasitária de tambaquis na região do Baixo São Francisco-AL/SE-Brasil e correlacionar os índices de prevalência e intensidade média com fatores bióticos e abióticos. Foram coletados 252 espécimes para análise parasitológica de 10 pisciculturas. Os parasitos foram contabilizados, identificados, e determinaram-se os índices de prevalência e intensidade média, que foram correlacionados com fatores bióticos e abióticos. Dos peixes coletados, 65,5% estavam parasitados por pelo menos um táxon. Foram encontrados 10 táxons: Monogeneas, Ichthyophthirius multifiliis, tricodinídeos, Piscinoodinium pillulare, Ichthyobodo sp., Dolops carvalhoi, Lernaea cyprinacea, Procamallanus (Spirocamallanus) inopinatus, Henneguya sp. e Myxobolus sp. As maiores prevalências foram encontradas para Monogeneas (49,2%) e Myxobolus sp. (31,5%). Correlações negativas entre prevalência e fatores bióticos (peso e comprimento) foram observadas para Monogeneas (r2= -0,49; r2= -0,43), Myxobolus sp. (r²= -0,46; r²= -0,39) e Henneguya sp. (r²= -0,41; r²= -0,39). O fator abiótico temperatura apresentou correlação negativa com as prevalências de Lernaea cyprinacea (r= -0,39) e tricodinídeos (r= -0,33), enquanto a condutividade elétrica apresentou correlação positiva (r= 0,40) com a prevalência de tricodinídeos. Conclui-se que a fauna parasitária dos tambaquis cultivados na região do Baixo São Francisco é diversificada e com a carga parasitária dependente da qualidade de água e do estágio de desenvolvimento dos peixes.
ABSTRACT:This study aimed to evaluate the stress and changes in white blood cell count of juveniles Oreochromis niloticus subjected to acute toxicity of diesel oil. The toxicity was evaluated in a completely randomized design with five dilutions (20, 25, 30, 35 and 40%) and one control, both with three replicates. For the assessment of blood glucose levels and changes in white blood cell count, blood was drawn by caudal puncture of the dying fish. It was concluded that diesel oil can present risks to aquatic ecosystem, causing toxicity and physiological changes to fish. KEYWORDS: physiological changes; fish; derived oil; leukogram. RESUMO:O presente trabalho teve como objetivo avaliar o estresse e as alterações no leucograma dos juvenis de Oreochromis niloticus submetidos à toxicidade aguda do óleo diesel. A toxicidade foi avaliada em um delineamento inteiramente casualizado com cinco diluições (20, 25, 30, 35 e 40%) e um controle, ambos com três repetições. Para a avaliação dos níveis glicêmicos e alteração no leucograma, foi retirado sangue por punção caudal dos peixes moribundos. Dessa forma, conclui-se que o óleo diesel pode apresentar riscos ao ecossistema aquático, provocando toxicidade aos organismos aquáticos e alterações fisiológicas. Alterações leucocitárias ocasionadas pelo estresse toxicológico agudo do óleo diesel em juvenis de tilápia-do-nilo PALAVRAS-CHAVE:
The aim of this study was to evaluate the antiprotozoal activity of essential oils from Varronia curassavica accessions against different stages of Ichthyophthirius multifiliis. Essential oils from each accession were tested in vitro at the concentrations 0, 10, 25, 50, 75, 100, and 200 mg/L. The VCUR-001, VCUR-202, VCUR-509, and VCUR-601 accessions presented the major compounds α-pinene, germacrene D-4-ol, (E)-caryophyllene and epiglobulol, and sabinene, respectively. These isolated compounds were tested in vitro at a concentration proportional to that found in the essential oil which caused 100% mortality of the parasite. The concentrations of 10 and 50 mg/L of the essential oil of accession VCUR-202 provided 100% mortality of trophonts and tomonts, respectively. For the accession VCUR-509, 100% mortality of trophonts and tomonts was observed at concentrations 75 and 200 mg/L of essential oil, respectively. The same mortality was observed at concentration 200 mg/L in both stages of the parasite for the other accessions. The major compounds α-pinene, sabinene, and the (E)-caryophyllene + epiglobulol mixture caused 100% mortality of trophonts and tomonts. The in vivo assay for white spot disease control was performed in a therapeutic bath of 1 h with the essential oil of accession VCUR-202 at concentrations of 0.5 and 2.0 mg/L. A significant reduction of about 30% of trophonts on infected fish was observed, independent of the oil concentration. The V. curassavica essential oil, especially the VCUR-202 accession, is a potential source of raw material for the formulation and commercialization of bioproducts to control freshwater white spot disease in fish.
This study evaluates the host-parasite-environment relationship between the parasitic nematode Procamallanus (Spirocamallanus) inopinatus and the fish host Bryconops melanurus, as well as reports the seasonal occurrence of the parasite in the host. The study was performed in a total of 78 fish collected from a tributary of Caeté River, Bragança, PA, Northern Brazil. The nematode was present in several organs (stomach, pyloric caecum, anterior intestine, posterior intestine) from 76 out of 78 fish specimens. For each location the prevalence and mean intensity of the infection are provided. The level of parasitism was not influenced by the month of capture, but higher parasitic loads were observed in pyloric caecum and posterior intestine during the rainy season (March to June 2007). Seasonal fish host-nematode relationship can be influenced by fish feeding behaviour patterns associated with flood period variations.
The occurrence of paratuberculosis infection has been well documented in non-ruminant wildlife, but in wild carnivores the studies about Map infection are scarce 5 . While a study of wild carnivores reported 38% direct PCR positive results, only in one tissue was viable Map isolated 6 . A recent study in Southwestern Europe showed little or no evidence of Map infection in wild canids 7 . Herein we confirm that Eurasian otters can be a carrier of mycobacteria, specifically of Map, which, to the best of our knowledge, was never described before.
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