جستجوی مقالات مرتبط با کلیدواژه « ماهی تیلاپیا » در نشریات گروه « شیلات »

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.

This study aimed to investigate the effect of different levels of prebiotic Pleurotus ostreatus on hematological indices of Nile tilapia, Oreochromis niloticus exposed to chlorpyrifos toxin.A total of120 fish were distributed for 42 days in 4 treatments (each with 3 replicates), including control (1), no prebiotic fungi, (2) food containing 0.05, (3) food containing 0.1 and (4) food contained 0.2% prebiotic. Then, 0.5 ppm of Chlorpyrifos was added to each group for 16 days and their blood parameters were examined. Based on the results, prebiotic alone had no significant effect on erythrocyte count, mean cell volume (MCV), hematocrit, hemoglobin, white blood cell (p < /em><0.05) but exposure to Chlorpyrifos 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 MCHC were higher than the other treatments in the combination of 0.2 and 0.1% prebiotic and Chlorpyrifos. It is concluded that the 0.1 and 0.2% prebiotic level could have the best effect on the blood indices of Nile tilapia.

In order to investigate the effect of dietary-vitamin on growth and immunity indices in Nile tilapia (Oreochromis niloticus) and lettuce (Lactuca sativa) in an aquaponics system, 240 tilapia pieces with the average weight of 12 ± 1.25g and 240 seedlings of lettuce were randomly introduced into nine experimental unites. The treatments were different rates of vitamin B3 concentration in the fish feed with the levels of 20, 40 and 60 mg per kg. Growth indices did not show any significant difference among treatments (P≥0.05). Lettuce growth indices such as final leaf length and final leaf width showed a significant difference among treatments (P <0.05). The plant final height, plant fresh weight, plant dry weight, root fresh weight and dry weight were not significantly different (P≥0.05). Biochemical parameters of blood in fish showed the highest mean concentration of total protein, glucose and triglyceride levels in treatment with 60 mg of vitamin per kg compared to other treatments (P <0.05) , however blood indices such as serum cortisol, alkaline phosphatase and aspartate aminotransferase contents were not significantly different (P≥0.05). It was concluded that, with increasing the vitamin B3 at the rates of 40 to 60 mg in feed, can improve tolerance of fish to stress and increase the fish growth and lettuce in the culture system.

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.

Viral disease in fish, especially Tilapia Lake Virus (TiLV) is a fatal disease with economic value. The emerging virus could be a serious threat to aquaculture of tilapia in Asia and around the world. Tilapia Lake Virus (TiLV) as an RNA virus and similar to Orthomyxovirus fish disease has clinical signs such as discoloration, scratches the skin and degeneration of the eye, loss of appetite, slowness of movement, impaired vision and dark lens, lethargy, endophthalmitis, corrosion skin, density in kidney, and encephalitis, congestion average of spleen and kidney, lesions in brain tissue contains edema, hemorrhage, focal, leptomeninges, and capillary congestion in both white and gray matter. Tilapia lake virus has RNA with negative sense and its genome has10 pieces. Biological studies have shown that direct transmission is very important as horizontally way. Viral diseases are a common cause of illness and death in farmed fish. So far mentioned virus is no risk to human health, but it can significantly reduce the population of infected fish. There is no way to treat it effectively, but learn more about the characteristics of patients that can be effective in preventing the virus transmission.

Fish freshness by using QIM and according to scoring to all of parts variable (positive and negative) was by sensory method and finally become the parameters of quantitative and qualitative with statistical analysis is based, tables used in volatility score of 0 to 23, with a score of 0 to 3 respectively, for their excellent quality, 3 to 7good, from 7 to 10 and from 10 to above average evaluation is unacceptable. In this study to measure the freshness of fish species Nile Tilapia (Oreochromis niloticus), black and red in 4 treatments, whole fish and empty stomach is considered and the objective of this study was to calculate the survival rate of fish in ice cover practically immediately after harvest to measure qualitative factors (sensory evaluation, chemical and microbiological).For this study 50 pieces of red and 50 pieces black Tilapia after weighed, washed and then selection 25 pieces for each treatment in unlit, ratio of 3 to 1 (ice - fish) was covered. The mean (± SD) change in temperature the fish flesh during study were between 0.2 ±0.07 a to 0.3 ±0.1a degrees Celsius, that need to raise the quality temperature is maintained at 0 degrees Celsius in unlit center. Fish covered with ice keep at ambient temperature, and after measuring the change free nitrogen, pH and microbial tests, the results showed maximum shelf life of whole fish in ice cover 9 and for empty stomach fish was7 days. And also statistical analysis (Duncan test) of data between treatments (Whole and empty fish covered in ice) was significant (P<0.05).