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1.
Growth of several genetically improved Nile tilapia (GIFT or Genetically Improved Farmed Tilapia, FaST or Freshwater Aquaculture Center Selected Tilapia, SEAFDEC-selected) and domesticated red tilapia (BFS or Binangonan Freshwater Station, NIFI-red or National Inland Fisheries Institute red, HL or Hacienda Luisita) stocks were compared in controlled (tank) and uncontrolled farm conditions (lake-based cages) with unselected NIFI or Chitralada Nile tilapia as control. Specific growth rate differed significantly (P = 0.009) in tank-reared Nile tilapia stocks where GIFT grew best at 1.358%/day followed by FaST (1.307%/day), control stock NIFI (1.257%/day) and SEAFDEC-selected (1.202%/day). Genetic effect explained 84.4% of the variance in growth of Nile tilapia in tanks. Although Nile tilapia growth in cages followed the same trend where GIFT grew best at 1.570%/day, no significant stock differences (P = 0.479) were noted. Meanwhile, red tilapia reared in either tanks or cages showed no significant stock differences in terms of growth. However, survival of the red tilapia stocks in cages differed significantly with HL having the highest percentage survival at 93.3%. The different growth responses of the Nile tilapia stocks especially under controlled (tank) farm conditions were largely due to genetic factors (stock differences).Under uncontrolled farm conditions, environmental factors were generally observed to have also affected the survival and to some extent, the growth of Asian Nile and red tilapia stocks.  相似文献   

2.
This experiment was conducted to evaluate the seminal characteristics of Nile tilapia males exposed to water‐borne 17α,20β‐dihydroxy‐4‐pregnen‐3‐one (17,20βP). Male Nile tilapia (Oreochromis niloticus L.) were exposed to the steroidal pre‐ovulatory pheromone 17,20βP, added to water at a concentration of 5×10?9 M. The pheromone‐exposed males had higher sperm volume and concentration. In addition, the spermatozoa contained in the sperm had higher motility and the motility duration was longer than ethanol‐exposed males (control group). The percentage of live spermatozoa was not affected by the treatments. Our results suggest that this pheromone can improve sperm quality characteristics and could become a non‐invasive method for enhancing spawning in Nile tilapia.  相似文献   

3.
Mass mortality has occurred among cultured Nile tilapia, Oreochromis niloticus, on fish farms in Manzala, Dakahlia province, Egypt, in the summer season, 2019. Moribund fish were reported with deep ulcers, septicaemic lesions and sampled for bacterial isolation. In this study, most isolates were subjected to bacteriological examination, antibiotic sensitivity test, 16S rRNA gene sequencing and histopathological examination. Following isolate identification, intraperitoneal challenge of Nile tilapia with a bacterial suspension 2 × 106 CFU/ml was performed. Samples from liver, spleen and kidney were collected for histological and biochemical analysis. The results showed a high similarity (99%) to Photobacterium damselae strains using phylogenetic analysis of 16S rRNA. P. damselae exhibited resistance to amoxicillin and erythromycin, as well it was highly sensitive to chloramphenicol and doxycycline. Moreover, haemorrhage, oedema, hemosiderosis and melanomacrophage activation in the liver and head kidney of infected fish were detected by light and electron microscopy. Also, significant higher levels of CAT and SOD in the spleen and head kidney, as well as the serum levels of NO were observed in experimentally challenged O. niloticus, compared to the control fish. Our data identified P. damselae for the first time from infected Nile tilapia, describing its sensitivity to a variety of antibiotics, histopathological alterations and oxidative stress impact, and it could be useful indicators for understanding P. damselae pathogenesis, which might provide a preventive efficacy for P. damselae.  相似文献   

4.
Nile tilapia (Oreochromis niloticus) is one of the most important cultured species worldwide. The research aims to clarify the feeding characteristics, such as daily feeding pattern of Nile tilapia using a self‐feeding technique. The feeding pattern was conducted under two rearing conditions, indoor treatments under a controlled light regime (LD 12:12) and constant water temperature (25°C), and outdoor treatments under natural conditions which consisted of duplicate trials with two periods each. The outdoor treatment was carried out from early summer through late autumn in Mie, Central Japan. Daily self‐feeding activity of Nile tilapia in indoor treatments was nearly daytime feeding pattern, synchronizing with the given photoperiod (24 hr). However, the self‐feeding activity in the outdoor experiments from early summer to early autumn was almost daytime feeding pattern, but it became less clear and shifted to a nighttime feeding profile in late autumn. The results revealed that Nile tilapia has a dualistic capacity for demand‐feeding both in light and dark phases. These results might have been caused by the seasonal change in light intensity and/or water temperature. Information obtained from the self‐feeding experiments enables us to identify the influence of environmental changes on the physiological condition of farmed fish through their expression of appetite.  相似文献   

5.
A 10‐week feeding trial was conducted to investigate the interaction between tilapia genotype and dietary protein level on the growth, feed utilization efficiency and body composition of Nile tilapia [Oreochromis niloticus L., F9 generation of genetically improved farmed tilapia (GIFT) strain] and red hybrid tilapia (Oreochromis sp.). Two isoenergetic diets (15.5 kJ g−1 diet) containing 25% or 35% crude protein were formulated and fed to triplicate groups of tilapia (12.8±0.2 g) at a fixed daily ration of 4% of their body weight. The growth performance of the GIFT tilapia fed 25% or 35% dietary protein was significantly higher (P<0.05) compared with red tilapia at either protein level. Increasing the dietary protein level by 10% led to a further 10% increase in the final weight of GIFT tilapia but no further increase was observed in the weight gain of red tilapia. Growth was influenced by the interaction between diet and tilapia genotype. Feed conversion ratios were 14% and 33% better in GIFT tilapia compared with red tilapia fed the 25% or 35% protein diet respectively. Protein efficiency ratio and net protein utilization were influenced by both diet and tilapia genotype, but not the interaction between the two. The apparent digestibility coefficients of dry matter and protein did not differ significantly between the two diets and tilapia genotypes but lipid digestibility was 1.2–4.7% higher for the GIFT tilapia. Tilapia whole‐body protein content was significantly influenced by both diet and tilapia genotype. The higher growth potential, better feed utilization efficiency and higher body protein content of GIFT tilapia compared with red tilapia should have a positive impact on tilapia farming in terms of production costs.  相似文献   

6.
We tested the effects of monochromatic light on the specific growth rate (SGR), feed intake and feed efficiency (FE) of juvenile pikeperch, Sander lucioperca (L.). Pikeperch were reared individually for 42 days in aquaria covered with blue, green, yellow or red gelatin filters or white paper (control; n =5). Linear regression analysis indicated a significant positive effect of longer wavelengths of light on the condition factor (CF), FE and SGR. The final weight, SGR and CF were significantly higher in fish reared under red than under white light, and FE was better under green, yellow and red light than under white light (Dunnett's post hoc test, P <0.05) while blue was comparable to white light in terms of the measured parameters. After the growth trial, the spectral sensitivity of photoreceptor cells in the retina was tested using microspectrophotometry, which revealed the presence of rods with λmax at ca. 530 nm and two cone classes, absorbing maximally at ca. 535 and 603 nm, all containing a porphyropsin-based pigment. These results suggest that the presence of mid and long wavelength-sensitive cones enhances visual sensitivity under mid-wavelength and long-wavelength environments, and thus supports the finding that longer wavelengths of incoming light can improve FE and SGR of the cultivated pikeperch.  相似文献   

7.
This study was conducted (1) to evaluate the effects of photoperiod (fixed vs. decreasing light), fish size (136 vs. 220 mm), dissolved ions (hardness and salinity) and diet (menhaden oil vs. coconut oil‐based) on the tolerance (survival) of Nile tilapia, Oreochromis niloticus, to low temperatures (decreased by approximately 0.5 °C per day) and (2) to evaluate the effect of dietary fatty acid composition on selected physiological characteristics of Nile tilapia exposed to decreasing temperatures. Size significantly affected mortality, with smaller fish being less tolerant to low temperatures than larger fish. Results were equivocal in the photoperiod, dissolved ion and dietary lipid experiments, and were dependent on the method of data analysis employed. Diet significantly affected plasma osmolarity, with higher values in fish fed the menhaden‐based diet. Haematocrit, serum glucose, sodium and cortisol concentrations, serum and splenic lysozyme activities, lymphocyte count and hepatosomatic index were not affected by diet. Haematocrit, white cell count and serum glucose and sodium concentrations were significantly affected by temperature, but serum and splenic lysozyme content, hepatosomatic index, and serum cortisol concentrations were not. The results of this series of experiments indicate that altering the environment or diet has little effect on the ability of Nile tilapia to survive low temperatures.  相似文献   

8.
A comparison was made of some productive traits of Stirling Nile tilapia (wild type) (Oreochromis niloticus, Linnaeus) and red hybrid tilapia (Florida red tilapia× Stirling red O. niloticus) males during a 98‐day grow‐out period. Twenty‐two males from each genetic group with initial weights of 139.0 g for O. niloticus and 207.3 g for the red hybrid were placed in triplicate tanks. The fish were fed with a feed containing 36.8% crude protein. Survival was 97.0% for the red hybrid and 83.3% for O. niloticus. Daily individual weight gains were 2.95 and 2.50 g and final body weights were 473.0 and 348.8 g for the red hybrid and O. niloticus respectively. Fillet yield was similar for both the species, with 33.4% for the red hybrid and 32.0% for O. niloticus. Fresh fillet lipid content was perceptibly less in the red hybrid (0.33%) than in O. niloticus (2.07%). Some benefits of a red low‐fat tilapia genotype are discussed.  相似文献   

9.
The present study was performed to evaluate the effect of vitamin C on the performance of Nile tilapia (Oreochromis niloticus) affected by the usage of engine oil. A total of 120 tilapia fish were randomly divided into four equal groups according to dietary treatments applied for 3 weeks: group I (control); group II was exposed to engine oil; group III was exposed to engine oil and supplemented with vitamin C: and group IV was fed only a diet supplemented with vitamin C. According to our results, the group exposed to engine oil (II) showed an induced elevation of kidney function parameters, an upregulation of CYP1A1 mRNA expression level, a reduction in antioxidant status (SOD, GSH) and severe abnormal histological and ultra‐structural changes in the head kidney, trunk kidney and muscle tissue. Supplementation of group III with vitamin C ameliorated the toxic effect induced by engine oil through improvement of kidney function parameters, elevation of the antioxidant status of tissue and improvement of the histological images of renal and muscle tissues. In conclusion, vitamin C has the ability to ameliorate engine oil oxidative stress toxicity in Nile tilapia.  相似文献   

10.
Two experiments were conducted to investigate the effects of feed colour on the performance of Nile tilapia (Oreochromis niloticus) larvae and fingerlings. In the first experiment, triplicate groups of newly hatched larvae (0.01 g fish−1) were stocked in 40 L glass aquaria at a density of 2 fish L−1. The fish were fed a test diet (400 g kg−1 crude protein) with six different colours (dark blue, dark green, red, dark brown, yellow and light brown) for 60 days. The best performance and survival were achieved in fish fed on dark‐coloured diets, while light‐coloured diets (yellow and light brown) resulted in inferior performance. Dark diets also produced higher body protein than light diets. Body water, lipids and ash showed irregular trends. In the second experiment, triplicate groups of Nile tilapia fingerlings (5.30 g fish−1) were stocked in 140‐L aquaria, in a recirculating indoor system. The fish were fed a test diet (350 g kg−1 crude protein) with the same colours used in the larval trial, for 60 days. Growth rates, feed efficiency, survival and body composition were not significantly affected by feed colours. These results suggest that Nile tilapia larvae are visual feeders, and they prefer dark‐coloured diets to light‐coloured diets, while fingerling fish showed no preference to diet colours.  相似文献   

11.
Although non‐native species can modify ecosystem function, their effects in southern China have not been investigated, despite their ecological importance. This study assessed how Nile tilapia Oreochromis niloticus (L.) invasions impact the functional patterns of fish communities in the large subtropical Pearl River by analysing the relationships between invasion and body size over a 9‐year period. The relative abundance of Nile tilapia increased significantly over time. In particular, the established Nile tilapia significantly undermined the relative densities and the body size of the native fishes. Importantly, this study provided empirical evidence that functional indices (such as body size) are more sensitive when evaluating the effects of non‐native species on a community than richness. Understanding processes such as those should be the basis of controlling alien fish species and fisheries management in the Pearl River.  相似文献   

12.
Fertilization of ultraviolet (UV) irradiated oocytes of Nile tilapia, Oreochromis niloticus (L.), with sperm from O, niloticus or blue tilapia, O, aureus (Steindachner), and subsequent suppression of the first cleavage of fertilized eggs successfully induced androgenesis in Nile and blue tilapia. The optimal doses of UV irradiation to denucleate a female genome of Nile tilapia prior to androgenesis ranged from 5940 to 6930 erg mm?2 for 54-63 s at a fixed intensity of 110 erg mm?2 s?1. Putative androgenetic fish were created from eggs which were irradiated at various times and several durations of heat-shock. Eggs which were treated for 5 min at 41.6 oC at 2 7.5 min after fertilization were the most successful at suppressing the first cleavage and producing viable androgenetic diploids in Nile or hybrid Nile X blue tilapia. The maximal survivals of putative androgenetic diploids in relation to the control were 1.60% and 0.90% in Nile and hybrid Nile X blue tilapia, respectively. The androgenetic offspring established exhibited active feeding and normal growth.  相似文献   

13.
The gustatory sensitivity of the Nile tilapia, Oreochromis niloticus L., to different amino acids was studied using an electrophysiological approach. The electrical responses were recorded from a branch of the facial nerve innervating the external taste buds of the upper lip. The relative stimulatory effectiveness (RSE) of nine amino acids and betaine were determined at a concentration of 1 mm and all of them elicited neural responses. This species responded well to the neutral, basic and acidic amino acids. The most stimulatory amino acids were L‐histidine, L‐arginine, L‐serine, L‐methionine and L‐glutamine; L‐proline and betaine were the least stimulatory. The results of this study suggest that the Nile tilapia has high external gustatory sensitivity to some amino acids as a physiological adaptation to search effectively for their sources. The effect of the pH, ranging from 4.0 to 9.0, on the RSE of three neutral amino acids and artificial pond water (APW) was also studied. The RSE increased below pH 6.0 and was relatively unaffected from 7.0 to 9.0, indicating that acidified stimulants are highly stimulatory in this species. Nile tilapia did not discriminate the pH of APW as effectively as some of the species studied earlier.  相似文献   

14.
A simulation model for the production of the Nile tilapia (Oreochromis niloticus niloticus L.) for mixed‐ or mono‐sex culture and for poly‐culture with the African catfish (Clarias gariepinus Burchell 1822) or African snakehead (Parachanna obscura Günther 1861) is presented. The model is based on an exponential decay model used in population dynamics and follows an individual‐based approach. The model consists of a tilapia sub‐model representing population dynamics, growth and recruitment and a predator sub‐model representing the predation process and population dynamics and growth of the used predator. The model was calibrated with data on mixed‐ or mono‐sex culture of Nile tilapia and for poly‐culture with the African catfish or African snakehead obtained in Congo Brazzaville and validated with similar data from the Philippines, Thailand and the Ivory Coast. The model visualized major underlying processes in tilapia farming and aspects for further improvement of the model; growth is one of the most sensitive input parameters and should be quantitatively related to feeding level and feed quality; length at first maturity and quantification of the recruitment of Nile tilapia has a relatively large influence and recruitment should be related to the length of the females; prey–predator relations are too coarse and should be more fine‐tuned with the relation between prey size and predator size. Incorporation of these features would provide the basis of a model that can serve as a predictive and decision‐making support tool.  相似文献   

15.
Francisella orientalis is a highly virulent, emerging bacterium that causes mass mortalities in tilapia. This pathogen also affects numerous other warm-water fish species, including three-line grunt, hybrid striped bass and various ornamental fish. This study sheds light on two new species of fish that are susceptible to F. orientalis. Asian seabass and largemouth bass showed variable levels of susceptibility in a bacterial challenge experiment. After intraperitoneally injected with a dose of 106 CFU/fish, a total of 64.28% and 21.42% mortalities were obtained in Asian seabass and largemouth bass, respectively. Meanwhile, Nile tilapia showed acute mortality of 100%. All fish showed typical lesions of francisellosis, including multifocal granulomas in the spleen and head kidney. Immunohistochemical analysis revealed strong positive signals inside the granulomas of all fish. The bacterial recovery in solid media from infected fish was highest in Nile tilapia (85.71%), followed by Asian seabass (35.71%) and largemouth bass (21.42%). PCR results tested 100% positive for Nile tilapia, and 78.57% and 21.42% for Asian seabass and largemouth bass, respectively. In conclusion, Asian seabass and largemouth bass are susceptible to this pathogen, which warrants new management strategies when employing predation polyculture systems of these species with tilapia.  相似文献   

16.
在水温9.0~16.0℃下,进行了2个室内受控实验,研究不同强度和颜色的光对仿刺参幼参（Apostichopus japonicus Selenka（）体质量0.10~0.17 g）聚集行为的影响。实验1：将仿刺参幼参放在覆以黑色塑料布的白色塑料水槽（50 cm×40 cm×30 cm）中,在距水槽7 cm的一端分别放置15 W、25 W、40 W、60 W和100 W的白炽灯泡,连续照射24 h,每隔2 h观察、记录仿刺参在水槽中不同区域的分布。实验2：在微流水的循环水槽中央的大方槽中放50头大小均一的健康仿刺参幼参,水槽底部有1.5 cm高的空隙与两侧的6个小方槽相通。5个小方槽中上方分别放红、黄、绿、蓝、白色的节能灯,波长分别为639、587、548和435 nm,另一个小方槽中无光照作对照。在循环水槽上方加盖不透光的厚纸板,12 h光照＋12 h黑暗,每隔3 h观察记录仿刺参在各小方槽中的数量,4 d为一个实验周期,重复8次。结果表明：在实验光照强度下,仿刺参均在距光源最远的Ⅳ区域中数目较多,其中40 W（光照强度为12~19 lx）时聚集的最多。仿刺参在红色光区的聚集数目明显高于其它光色区,其中红光与蓝光、白光差异极显著（P〈0.01）,红光与黑暗对照差异显著（P〈0.05）,白光与绿光差异显著（P〈0.05）。实验发现,红色光为仿刺参敏感的光色。  相似文献   

17.
Detection of tilapia lake virus (TiLV) in tilapines is mainly from visceral organs of killed fish. However, lethal sampling might not be viable to broodstock and economically important ornamental cichlids. To contribute towards screening of the virus in asymptomatic infected fish, a subclinically infected population of Nile tilapia adults obtained from a local farm was preliminarily tested to compare different non‐lethal sampling methods, for example liver biopsy, gill biopsy, fin clip, mucus, faeces and blood for detection of TiLV. Only liver and blood samples gave positive results by PCR. Since blood sampling is relatively simpler, it was further used for five naturally co‐cultured juvenile fish species from above‐mentioned farm including 40 red tilapia broodstock and 20 Nile tilapia adults from two other different farms. The results showed that from the tested fish, 4 of 5 Nile tilapia, 2 of 5 hybrid red tilapia and 3 of 5 giant gourami blood samples tested positive, while 38 of 40 blood samples of red tilapia tested positive for TiLV in second‐step PCR. Sequencing representative PCR amplicons of positive samples confirmed sequence identity to TiLV. In conclusion, both blood and liver biopsy are practical non‐destructive sampling platforms for TiLV screening in cichlids with blood being more convenient, especially for tilapia broodstock.  相似文献   

18.

以‘吉富’、‘新吉富’、‘埃及尼罗’3种不同品系尼罗罗非鱼(Oreochromis niloticus)为研究对象, 通过不同品系之间生长与高密度胁迫反应的比较, 探讨3种尼罗罗非鱼的生长特点与应激后生理响应的变化规律。将初始规格基本一致的3种品系尼罗罗非鱼饲养100 d后, 吉富罗非鱼特定生长率最高, 新吉富其次, 两者间无显著差异(P>0.05), 埃及尼罗罗非鱼特定生长率显著低于吉富罗非鱼(P<0.05)。吉富与新吉富罗非鱼的内脏比显著高于埃及尼罗(P<0.05); 3种尼罗罗非鱼的肥满度之间无显著差异(P>0.05)。养殖实验结束后, 进行48 h的急性高密度(100 g/L)应激实验。应激48 h内, 吉富与新吉富罗非鱼血清总蛋白、葡萄糖、谷草转氨酶、胆固醇与溶菌酶活力/水平以及肝HSP70mRNA水平呈先上升后下降的变化。应激48 h后, 埃及尼罗罗非鱼血清皮质醇水平与应激前相比无显著差异(P>0.05), 吉富与新吉富罗非鱼的皮质醇水平显著高于应激前(P<0.05); 埃及尼罗罗非鱼血清溶菌酶活力与肝HSP70 mRNA水平在应激后48 h内始终高于应激前(P<0.05)。研究结果表明, 短期高密度胁迫可提高3种尼罗罗非鱼血清葡萄糖与甘油三酯的利用, 并诱发肝损伤。埃及尼罗罗非鱼的抗高密度应激能力高于吉富和新吉富罗非鱼。

  相似文献   

19.
强俊  杨弘  王辉  徐跑  柒壮林  何杰 《水产学报》2012,36(6):958-968
以吉富罗非鱼、新吉富罗非鱼、埃及尼罗罗非鱼和红罗非鱼为研究对象,饲养100d后,进行海豚链球菌(2.95×108CFU/mL)感染试验,分析攻毒前后各品系罗非鱼的血液生化指标和肝脏HSP70 mRNA表达量的变化规律。另从各桶中取20尾鱼进行同样的攻毒试验,统计攻毒后各时间点的累积死亡率。结果表明,感染海豚链球菌96h后,吉富罗非鱼和新吉富罗非鱼对病原较为敏感,累积死亡率分别达到36.67%和38.33%;埃及尼罗罗非鱼对病原敏感性较差,试验期间未见死亡。吉富罗非鱼、新吉富罗非鱼和红罗非鱼血清皮质醇和葡萄糖水平以及肝脏HSP70 mRNA的表达量在攻毒后明显提高,血清谷丙转氨酶、谷草转氨酶与溶菌酶活力也呈上升趋势,碱性磷酸酶活力与甘油三酯和胆固醇水平低于攻毒前。埃及尼罗罗非鱼可以利用糖原和脂类产生的能量,提高了HSPS与一些特定免疫蛋白(溶菌酶、球蛋白等)的合成,增强了鱼体的非特异性免疫力。罗非鱼选育过程中,需要将抗病力与生长性能进行有效的结合,在注重生长速度的同时也要增强其抗应激能力,从而为罗非鱼产业的可持续发展提供保证。  相似文献   

20.
尼罗罗非鱼肌肉蛋白质双向电泳体系的建立   总被引：1，自引：1，他引：0  
为建立1种尼罗罗非鱼肌肉组织蛋白质的双向电泳体系,实验将尼罗罗非鱼肌肉组织蛋白质提取后,用双向电泳(2-DE)分离蛋白质,分别对蛋白质样品的制备方法、IPG胶条长度及p H范围、SDS-PAGE凝胶浓度及染色方法4个关键因素进行了探索和优化。结果显示,采用液氮研磨-丙酮沉淀法制备样品蛋白质,使用24 cm p H 4~7的IPG胶条进行第一向等电聚焦电泳,第二向SDS-PAGE电泳采用浓度为12.5%的凝胶进行,双向电泳后的凝胶采用硝酸银染色法进行染色处理,该条件下扫描所得尼罗罗非鱼肌肉蛋白质二维电泳图谱具有蛋白质分离程度好、斑点清晰、分辨率高及横纹少等优点。研究表明,技术体系适用于尼罗罗非鱼肌肉蛋白质的分离,可用于后续罗非鱼肌肉蛋白质组学研究。  相似文献   

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