Studies related to nictemeral variation were executed in a fish growing pond, during all the seasons of the year, collecting data for dissolved oxygen; temperature; pH and electrical conductivity at the feeding channel on pond's surface, bottom and at streamlet bed. The results showed that Autumn was the season which had the lowest values of water temperature, the interval points, during Spring...

In order to study the water quality in fish tanks, a 166-day (January to July 1992) experiment was realized using the indigenous species "p acu" (Piaractus mesopotamicus). Two different protein levels were tested in the diet (16% and 34% crude protein) and three stocking densities (0.25, 0.50 and 0.77 fish/m2). From the results, it was observed that the interactions between stocking density and...

O Piaractus mesopotamicus é um peixe endêmico da bacia dos rios Paraná-Paraguai, apresentado boa adaptação em sistema intensivo de produção. Nesses sistemas, a amônia pode alcançar níveis extremos quando atividades nutricionais e manejos não são corretas. Neste sentido, o objetivo do presente estudo foi avaliar capacidade tolerância P. expostos diferentes concentrações seu efeito na glicemia co...

This study evaluated the toxicity of hexavalent and trivalent compounds of chromium to the pacu, Piaractus mesopotamicus, in acute exposures of 96 h through mortality and histopathological responses. Hexavalent potassium dichromate was more toxic than trivalent compounds of chromium chloride, chromium oxide and chromium carbochelate. Sufficient mortalities occurred only with potassium dichromat...

Three species of freshwater Brazilian fishes (pacu, Piaractus mesopotamicus; piavussu, Leporinus macrocephalus, and curimbatá, Prochilodus lineatus) were exposed to an acute dose of 5 ppm methyl parathion organophosphate pesticide. Three to five individuals per species were exposed, one at a time, to 40 liters tap water spiked with Folidol 600. Pesticide concentrations and cholinesterase (ChE) ...

The effects of capture (chasing, netting and air exposure) on cortisol, glucose, chloride, sodium, potassium and calcium concentrations, osmolality, hematocrit, hemoglobin concentration, red blood cells count (RBC) and mean corpuscular volume (MCV) were investigated in pacu (Piaractus mesopotamicus). A total of 132 fish (49.7 +/- 11.7 g) were subjected to capture and 3 minutes air exposure and ...

The objective of this study was to evaluate the methodology to establish the hemolytic activity of alternative complement pathway as an indicator of the innate immunity in Brazilian fish pacu (Piaractus mesopotamicus), in addition to verifying the influence of β-glucan as an immunostimulant. Fish were fed with diets containing 0, 0.1 and 1% β-glucan, during seven days, and then inoculated with ...

This study evaluated the parasitism by Anacanthorus penilabiatus (Monogenoidea) and Piscinoodinium pillulare (Dinoflagellida) in the gills of “pacu”, Piaractus mesopotamicus supplemented with chromium in the diet. Randomised delineation by using factorial scheme (4x2x2) for Monogenoidea and 4x2x3 for Dinoflagellate with four levels of chromium (0, 6, 12, 18mg/kg diet), two stocking densities (4...

The intensive aquaculture needs accurate information on the identification and control of stress situations and/or diseases in order to ensure healthy fishes. The evaluation of blood parameters is the fastest way to detect stress symptoms. In this paper the hematocrit, hemoglobin concentration, mean corpuscular hemoglobin concentration (MCHC), differential count of defense cells (leucocytes and...

This assay evaluated the control efficacy of diflubenzuron, praziquantel and levamisole added to the diet of pacu (Piaractus mesoptamicus) infected with Anacanthorus penilabiatus and Dolops carvalhoi. 19 water tanks of 300 L capacity were utilized with 28 fish in each one. The treatments were made by mixing the active principles in the diet. The experiment was evaluated in four harvests done 1 ...