جستجوی مقالات مرتبط با کلیدواژه « Tilapia » در نشریات گروه « زیست شناسی »

Tilapias are the most well-known invasive fish in the world, impacting natural ecosystems, due to their high reproductive rate, omnivorous nature and high resistance to environmental conditions, pollution and disease and become serious competitors for native species. On the other hand, these fish are relatively cheap and delicious which make them very popular among fish breeders, due to their low cost. Based on scientific research, there are concerns about the fat content of these fish. Tilapia has much less omega-3 fatty acids and more omega-6s than other fish, which can cause heart disease, cancer and other chronic problems. While many native fish and some farmed fish, such as trout, die in contaminated water, tilapia can survive and even breed in contaminated water, resulting in absorption and bioaccumulation of contaminants into the fish body, which can be transmited to humans. In general, many experts believe that the consumption and breeding of tilapias are harmful to human health and aquatic ecosystems.Therefore,, farming of tilapia in the country has no economic or environmental justification

Today, the development of aquaculture activities has led to the transfer of many aquatic species to different countries. Due to its special geographical location and the development of these activities, Iran has been exposed to the invasion of exotic and invasive species. Considering the necessary permits for the development of tilapia farming by the Fisheries Organization in Iran and on the other hand, the ecological consequences of these exotic fish and invading the domestic ecosystems of Iran, it is necessary to provide comprehensive information about this group of fish for the scientific community. With this in mind, the authors of this paper decided to review a book recently published by Springer International Publishing in 2021 on cichlids. The title of the book is "Behavior, ecology and evolution of cichlid fish" which has studied the biological, ecological and evolutionary characteristics of cichlid fish from different perspectives. This paper proposes the book as an ideal and valid reference on cichlids or tilapias for the scientific community of the country due to its comprehensiveness in the subject.

The aim of this study was to investigate the effect of different prebiotic levels of oyster mushroom (Pleurotus ostreatus) on hematological indices of Nil tilapia exposed to silver nitrate. For this purpose, 120 juveniles of tilapia were fed with diet containing 0 (treatment 1, control), 0.05 (treatment 2), 0.1 (treatment 3) and 0.2% (treatment 4) prebiotic oyster mushroom) for 42 days. Then, 0.5ppm of silver nitrate was added to each group for 16 days. Before and after exposing to silver nitrate, fish blood indices were evaluated. Prebiotics alone had no significant effect on RBC, MCV, hematocrit and hemoglobin (P<0.05). But, treatments fed with prebiotics and exposure to silver nitrate toxin showed an increase in WBC, MCHC (in 0.1 and 0.2 treatments), MCH indices compared to the control group. According to the results, oral prebiotics stimulated nonspecific immunity in tilapia and using mushroom prebiotics reduced the destructive effects of the silver nitrate toxin on blood indices. In conclusion, levels of 0.1 and 0.2% of prebiotic oyster mushroom in treatments which exposed to 0.5ppm silver nitrate toxin could improve the blood factor status of tilapia.

Emerging contaminants of nanoparticles in aquatic ecosystems cause stress response in aquatic animals and decrease their immune function. Therefore, use of immune stimuli such as prebiotics is very necessary. The aim of this study was to investigate the effect of different levels of prebiotic Pleurotus ostreatus on hematological indices of tilapia (Oreochromis niloticus) exposed to silver nanoparticles.

120 fish were distributed for 42 days in 4 treatments (3 replicates): control (1), no prebiotic fungi, treatment (2) food containing 0.05, treatment (3) food containing 0.1 and treatment (4) food contained 0.2% prebiotic. Then, 0.5 ppm of silver nanoparticles was exposed to each group for 16 days and blood parameters were examined.

Prebiotic alone had no significant effect on erythrocyte count, mean cell volume (MCV), mean cell hemoglobin (MCH), mean erythrocyte hemoglobin concentration (MCHC), hematocrit, hemoglobin, white blood cell (P <0.05) but exposure to silver nanoparticles and prebiotic in combination increased the mentioned factors compared to the control and prebiotic treatments alone. However, the levels of white blood cells and erythrocytes, hemoglobin, hematocrit, and MCH were higher than the other treatments in the combination of 0.2 prebiotic and silver nanoparticles.

Oral probiotics stimulate non-specific immunity in tilapia, the combined use of nano-silver and prebiotic mushrooms increase the amount of blood indices and reduce the destructive effects of nano-silver on blood indices. It is concluded that the 0.2% prebiotic level could have the best effect on the blood indices of tilapia.

The aim of the present study was the environmental impact assessment of tilapia (Oreochromis niloticus) farming in suitable areas of Yazd province. This research was conducted to achieve appropriate use of these resources, employment and development of central less developed regions of Iran along with identifying the human and ecological effects of its implementation in order to minimize environmental impacts as well as economic and social justification. A total area of about 100 ha including 6 farms was selected. Matrix method was utilized for the environmental impact assessment. Considering the executed studies and results of operation phase matrix, no considerable destructive impacts were observed related to the project. Due to the fact that 50% of means in rows and columns of the matrix were not less than -3.1, we proposed execution of this project with rehabilitation plans.