جستجوی مقالات مرتبط با کلیدواژه « tilapia » در نشریات گروه « کشاورزی »

Contaminants in aquatic ecosystems cause tissue damage in fish. In some cases, the effects of pesticide degradation on non-target organisms (aquatic) are greater than on target organisms (pests), which in turn causes faster and more aquatic deaths. The use of safety stimuli seems to be essential. The aim of this study was to investigate the effect of different prebiotic levels of Pleurotus ostreatus on histological characteristics of tilapia (Oreochromis niloticus) exposed to chlorpyrifos. This research was conducted in the fall of 2019. For this purpose, 120 tilapia fry were divided into 4 treatments for 42 days. Then, 0.5 ppm concentration of chlorpyrifos was added to each group for 16 days. At the end of the period, the fish were anesthetized with clove anesthetic solution (220 mg / l) and their liver tissue and gills were isolated for histological studies.  The results showed that the treatments exposed to 0.5 ppm chlorpyrifos (poisoned control without prebiotics) had the most destructive effect on liver and gill tissue. However, combined prebiotic treatments of Pleurotus ostreatus and chlorpyrifos improved tissue damage, indicating detoxification, and a concentration of 0.2 ppt Pleurotus ostreatus had the best performance against tissue damage to the liver and gills of tilapia, indicating improved resistance.

The aim of the present study is to evaluate the amount of tilapia fish consumption and the relationship between its consumption amount and some demographic characteristics Such as gender, age, occupation, education, marital status, occupation, number of household members and income.

The statistical population of this research is the whole country. A questionnaire was designed and sent to people electronically through virtual space. Correlation tests were used to evaluate the number of fish purchases per year as well as the amount of each purchase from the output of SPSS software and to investigate the existence of a significant relationship between consumption and demographic characteristics.

The results showed that Most of the female respondents are married, aged 20 to 35, employed and have bachelor's and master's degrees. Most of them are employees and earn between 3 and 6 million tomans. It was also found that most households (54%) buy fish up to 20 times a year. The average number of times of buying fish per year by the households of the consumption community was 45 times. Most households in the consumer society buy 2 kg of fish each time they buy. The number of households that consume more than 10 kg of fish per purchase was 3.3%. According to the obtained information, the average amount of fish per purchase was calculated to be 8 kg. The per capita consumption of tilapia in households consuming this fish was 4.2 kg.

The growing worldwide population has led to an increase in food query and aquaculture is one of the production sectors to supply feed required by the world. It is thought the aquaculture should be maintainable. However, the expansion of a sustainable aquaculture commerce has been hindered by the restricted accessibility of natural resources as well as its undesirable impact on the surrounding environment. The prime goal of aquaculture expansion must be to produce more product deprived of significantly increasing the usage of the basic natural resources of water and the land. The second goal is to develop sustainable aquaculture system that will not destruct the environment. The third goal is to built up systems providing an equitable cost/benefit ratio to support economic and social sustainability. Thus, there is a crucial need to search for better aquaculture production systems. All these three fundamentals for sustainable aquaculture development can be met by biofloc technology

This study is designed to investigate the effects of slow and quick freezing on fatty acids and microbial load of Oreochromis niloticus. Fillets were prepared in groups of slow and quick freezed and were preserved in -18ᵒ centigrade for six months. Changes in Fatty acids amounts and microbial load were monitored every month. Our results indicate statistically significant changes in fatty acid amounts during cold-room preservation in all tested samples. Fresh fillets of O.niloticus contain 24.84 percent of sutured fatty acids (SFAs), 36.14 percent of mono unsutured fatty acids (MUFAs) and 38.62 percent of poly un-sutured fatty acids (PUFAs). However, in the last month of sampling, SFA and MUFA levels significantly increased; whereas PUFA level decreased (p<0.05). In slow and quick freezed O.niloticus, SFA increased to 28.90% and 27.38%, MUFA reached 39.55% and 38.21%, and PUFA decreased to 30.56% and 35.22%, respetively. Changes in fatty acid levels were significantly less severe in fillets with quick freezing method (p<0.05). The results of total count indicate that quick freezed samples had lower numbers of microbial load in comparison with slow ones (p<0.05).

An experiment was conducted to evaluate the effect of biofloc system on water quality, growth performance, immunity and body composition of Nile tilapia at different stocking densities. Fry (3.2±0.05 g) stocked in 500 and 1000/m3 in biofloc and clear water system (as control) in three replicates and reared for 50 days. Results showed that the lowest TAN and highest nitrite and nitrate were observed in BFT treatments. Total suspended solid, floc volume and bacteria increased by increasing stocking density. Maximum final weight (12.9g), SGR (3.21 %/day), survival (100%) and the best FCR (0.91) were obtained in BFT (500/m3). There were no significant differences in survival among treatments (p>0.05). Lysozyme, immunoglobulin and catalase of fishes in the biofloc treatments were significantly (p<0.05) better than control. Proximate analysis revealed that protein and lipid content of fishes in BFT were slightly higher than control groups but these differences were not significant. It seems that although fishes in BFT 500/m3 statistically showed better indices than others but due to small differences in growth indices and feed conversion ratio in one hand and no difference in survival rate between 500 and 1000/m3. On the other hands, the study suggests the stocking density of 1000/m3 for larviculture of tilapia in biofloc system to use water and equipment more efficiently.

The efficacy of supplementary diet with a mixture of Bacillus spp. and Lactobacillus spp. probiotics in enhancing water quality, growth performances, serum and skin mucus parameters of Nile tilapia (Oreochromis niloticus) was investigated in four treatments: T1- water exchange system without probiotics; T2, water exchange system with probiotics; T3, zero-exchange biofloc system with probiotics; T4, zero-exchange biofloc system without probiotics, for a period of 90 days. At the end of study, the mean final weight, weight gain, specific growth rate, and feed conversion rates were found significantly (P<0.05) higher in biofloc-based treatments (T3 and T4) versus tanks with water exchange (T1 and T2). The mean values of total ammonia nitrogen (TAN) concentrations and pH were significantly lower in tanks with water exchange (T1 and T2) compared to biofloc treatments (T3 and T4), Meanwhile, probiotic application showed to significantly improve serum immune responses (ACH50 and superoxide dismutase) and skin mucus parameters (total protein, total immunoglobulins, protease activity, lysozyme activity and alkaline phosphatase activity) in both systems. In conclusion, biofloc technology and dietary probiotic administration beneficially enhanced the growth performances as well as serum and skin mucus immune responses of tilapia.

Aquaculture development during the last decades has led to an increase in aquaculture effluents into water bodies. Treatment of these effluents and reusing them in culture systems can decrease the level of destructive impacts on aquatic ecosystems. The present study was conducted to investigate the possibility of using phyto- and zooplankton microorganisms to treat and reuse fish culture wastewater in an integrated culture system. The Nile tilapia (Oreochromis niloticus) and Chlorella vulgaris were used as fish and microalgae species. The main zooplankton classes were composed of artemia (Artemia franciscana) and rotifer (Brachionus sp.). Measured and calculated parameters were: nitrate (NO3), nitrite (NO2), ammonium (NH4), phosphate (PO4), dissolved oxygen (DO), pH, electrical conductivity (EC), total dissolved solids (TDS), total suspended solids (TSS), number of microalgae cells and zooplankton counts, and fish growth performance parameters include weight gain (WG), specific growth rate (SGR) and condition factor (CF). The results showed that nutrient levels (NO2, NO3, and PO4) were significantly (P < 0.05) lower at the system outlet than control condition during the study period. The DO and pH levels were observed at their optimum ranges (DO > 6 mg.l-1; pH = 7 - 8) during the study period. The levels of EC, TDS and TSS of the integrated system were significantly (P < 0.05) lower than the control condition. The growth performance (i.e. weight gain) of fish was significantly (P < 0.05) better in the integrated system compared to the control condition. It can be said, based on the obtained results, simultaneous use of microalgae, zooplankton, and fish in an integrated tilapia culture system was led to the appropriate treatment of fish culture effluent and significant improvement of water quality to reuse in the system without any undesirable effect on fish growth compared to the control condition.

Aquaculture diseases and its damages have affected the aquaculture industry around the world. Tilapia is newly introduced to the aquaculture industry of Iran. While tilapia is a tolerant fish, there are reports of infectious diseases, and it is essential to plan for their prevention and control. Health surveys of tilapia breeding indoor systems were carried out at the National Research Center of Saline Water Aquatics (Bafq, Yazd) in 2012-2014. Parasitic, bacterial, fungal and viral studies of eggs, fries, brooders and cultured fish were performed by observing abnormal movement, nutrition and symptoms of the fish as well as unusual mortality. Infection with parasitic agents Gyrodactylus sp. and Dactylogyrus sp., bacterial agents Streoptococcus sp. and Edwardsiella sp. and fungi of Penicillium sp. and Aspergillus sp. determined. The samples were negative for Herpesvirus, EHNV and BIV viruses. Although pathogens and disease factors have been rarely observed in the Nile tilapia Oreochromis niloticus and red hybrid tilapia, monitoring and enforcement of health guidelines is particularly important in preventing disease.

Malathion is one of the agricultural organophosphate pesticides used in agriculture that may be found in aquaculture centers. The aim of this study was to investigate the effects of different levels of dietary vitamin C on improving the situation of growth, digestive enzymes activity and blood stress factors of Nile Tilapia (Oreochromis Niloticus) under sub-lethal toxicity of malathion.

In this experimental study, 180 Nile tilapia with weight average of 12.5±5g were subjected to 25% concentrations of Lc50 96h of malathion for 28 days and during this period, the fishes were fed with different levels of vitamin C (0, 300, 600, and 900mg/kg of feed). Data were analyzed by Duncan's new multiple range test and one-way analysis of variance through SPSS 24 software.

The weight gain and specific growth rate of fish fed by the highest vitamin level (900mg/kg of feed) were significantly higher than other groups (p<0.05), while the feed conversion ratio in the fish under mentioned treatment significantly decreased compared to other treatments. Trypsin and chymotrypsin digestive enzyme activities were significantly increased in treatments of 600 and 900mg/kg vitamin C in diet, respectively. The activity of other enzymes at different concentrations of vitamin C in the diet did not show a significant difference (p>0.05). Blood glucose level was significantly higher in control treatment in comparison to the other treatments.

Vitamin C as an anti-stress agent reduces the stress in Nile tilapia subjected by Malathion pesticides and improve the metabolic status and growth performance of Nile tilapia.