Use of mathematical models in the study of bodily growth in GIFT strain Nile tilapia

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Does sex influence intraspecific aggression and dominance in Nile tilapia juveniles?

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Temporal and Spatial Variability of Limnological Characteristics in Areas under the Influence of Tilapia Cages in the Chavantes Reservoir, Paranapanema River, Brazil

The influence of tilapia cages on limnological characteristics of the Chavantes Reservoir, Paranapanema River, Brazil, was investigated in March and June 2007. Principal components analysis was used to compare the transparency; dissolved oxygen; temperature; total organic nitrogen, phosphorus, and dissolved solids; chlorophyll aand electrical conductivity of fish farm 1 (239.3m.t.), 2 (461.5m.t.) and areas without cages, in the lacustrine and river-reservoir transition regions. The variables differentiated the regions and areas with and without cages. In March, in the lacustrine region, there was a thermal and chemical stratification, and in the transition region, there was a temperature and oxygen reduction gradient between the surface and bottom that was also observed in June in fish farm 1. The higher transparency confirmed the increased light penetration in the lacustrine region. In the transition region, there were higher turbidity, total dissolved solid, and conductivity values that are likely related to allochthonous material flow and transport. In fish farms, lower oxygen and pH values indicate intense decomposition and respiration. The generally higher total dissolved solid and nutrient values, turbidity, and conductivity and the lower transparency in one or both fish farms indicate their contribution to eutrophication, demonstrating the need for careful monitoring.

Emergy assessment of tilapia cage farming in a hydroelectric reservoir

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Acute aerocystitis in Nile tilapia bred in net cages and supplemented with chromium carbochelate and Saccharomyces cerevisiae

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of glyceryl guaiacolate ether on anesthetics in tilapia compared to benzocaine and eugenol

Objective. The study aimed to investigate the effectiveness of glyceryl guaiacolate ether (GGE) and compare the times of induction, recovery, hematological changes, total protein and glycaemia among anesthetics in Nile tilapia, Oreochromis niloticus. Materials and methods. A total of 60 tilapia distributed in 3 aquariums (N=20) were used, which formed the group benzocaine (100 mg/L), eugenol (50 mg/L) and guaiacol glyceryl ether (9.000 mg/L). After the induction of anesthesia fish blood samples were collected to determine the complete hemogram and glycemia. Then the animals were placed in aquariums with running water for assessing the anesthesia recovery. Results. It was verified that GGE showed longer induction and recovery times as well a significant increase (p<0.05) of glycemia, when compared with the other groups (p<0.05). The concentration of total protein did not differ between groups (p>0.05). An increase in the number of monocytes in the group treated with benzocaine (p<0.05) was observed in the analysis of the hematological parameters with no difference between groups for other variables. Conclusions. Eugenol and benzocaine allow rapid induction and recovery in Nile tilapia, without evidence of stress during handling and GGE showed high induction and recovery times, being inadequate for anesthetic use in Nile tilapia.

Low Dose of the Anesthetic Propofol Does Not Induce Genotoxic or Mutagenic Effects in Nile Tilapia

We demonstrate the efficacy of propofol (2,6-diisopropylphenol) as an anesthetic when administered to fish in an immersion bath and show the absence of genetic side effects following short-term exposure to the drug. All tested fish were anesthetized (as indicated by loss of posture and lack of response to physical stimulation), and both the comet assay (tail intensity) and the micronucleus assay revealed that propofol does not induce primary DNA damage or chromosome damage in the fish Nile Tilapia Oreochromis niloticus. Our results should be considered in light of our particular test conditions, including the water temperature (similar to 25 degrees C), the life stage and size of the fish, and the single exposure to the anesthetic. We suggest that propofol is a promising anesthetic in terms of its lack of genotoxic effects, at least in low dosages in adult Nile Tilapia.Received June 25, 2013; accepted October 15, 2013

Redox dysregulation and bioaccumulation of copper in tilapia Oreocromis niloticus

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Microbiological quality of whole and filleted shelf-tilapia

Despite fish being a rich source of animal nutrients and having numerous associated health benefits, it is an extremely perishable food, prone to a wide range of hazards. The bacterial load associated with shelf-whole-fish organs (e.g. digestive tracts and skin) or mishandling of fish may be a vehicle of infection and become a risk to public health. The objective of this paper is to evaluate the microbiological quality of whole ungutted and filleted shelf-tilapia, as well as assess the safety for human consumption. For this purpose, in order to investigate the distribution and occurrence of bacterial populations, the count of total and thermotolerant coliforms, coagulase-positive Staphylococcus and presence of Salmonella spp. was determined. This paper shows that all fish organs were contaminated with thermotolerant coliform. Skin and fillet show higher populations and occurrence of all microorganisms analyzed. Lower bacterial populations were recovered from the gut and muscles of whole tilapia. Two samples of fillet were contaminated with coagulase-positive Staphylococcus. It can be concluded that the skin and filleted tilapia are important carriers of food-borne pathogens. In addition, fish might become an important cross and self-contamination source. (C) 2014 Elsevier B.V. All rights reserved.

Polyculture of frogs and tilapia in cages with high feeding frequency

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Sugar cane vinasse in water bodies: Impact assessed by liver histopathology in tilapia

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Non-specific immune parameters and physiological response of Nile tilapia fed beta-glucan and vitamin C for different periods and submitted to stress and bacterial challenge

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Substratum choice for nesting in male Nile tilapia Oreochromis niloticus

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A influência do enriquecimento ambiental no comportamento agressivo da tilápia do Congo Tilapia rendalli

O enriquecimento ambiental tem sido proposto como uma prática para melhoria do bem-estar de animais de cativeiro ou de produções zootécnicas. No caso de animais territoriais e agressivos, ao se enriquecer o ambiente, aumenta-se a quantidade de recursos a se defender, bem como o valor do território em disputa, aumentando as interações agressivas. Esse aspecto foi mostrado recentemente para o peixe ciclídeo tilápia-do-Nilo (Oreochromis niloticus). Do ponto de vista comparativo, isso pode ser um fenômeno espécie-específico. Para avaliar isso devemos observar se em condições similares outro peixe ciclídeo sofre a mesma influência do enriquecimento do ambiente. Assim, seguindo a lógica do confronto obtido para tilápia-do-Nilo, aventamos a hipótese de que as atividades agressivas aumentam em função do enriquecimento. Este estudo avaliou essa hipótese para a tilápia do Congo Tilapia rendalli. Como principal resultado, observamos que a latência para iniciar a luta é menor no ambiente enriquecido, mas a frequência de ataques é maior no ambiente não enriquecido (controle). Além disso, observamos clara definição hierárquica por meio da sinalização de submissão (corpo com listras escuras) e dominância (corpo claro sem listras) na condição sem enriquecimento do ambiente. Concluímos que ao contrário da tilápia-do-Nilo, na tilápia do Congo o enriquecimento do ambiente leva a diminuição da agressividade sem clara definição da hierarquia de dominância

PROD and BROD modulation in Nile tilapia after exposure to 17 beta-estradiol

The activities of 7-ethoxyresorufin-O-deetylase (EROD), 7-benzyloxyresorufin-O-debenzylase (BROD), 7-pentoxyresorufin-O-depentilase (PROD), and glutathione S-transferase (GST) were measured in Nile tilapias exposed for 7 days of 5 and 15 μg/L 17 β-estradiol. EROD and GST activities were unchanged. PROD activity increased in animals exposed to the higher dose of the hormone, while BROD was increased after 7 exposure days to both doses of the compound. These results indicate the usefulness of these enzymes as biomarkers for 17 β-estradiol exposure.