scholarly journals Pathological and electron microscopic studies on cold water disease among cultured rainbow trout (Oncorhynchus Mykiss Walbaum)

2013 ◽  
Vol 3 (1) ◽  
pp. 2 ◽  
Author(s):  
Salah Mesalhy Aly ◽  
Wael G. Nouh ◽  
Nashwa Abdel Atti ◽  
Ahmed M. El-Ashram
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Cold Water ◽  
Control Measures ◽  
Electron Microscopic ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Microscopic Studies ◽  
Ion Imbalance ◽  
And Control ◽  
Private Farm

The present study aims to investigate the etiology and pathogenesis of cold water disease among cultured rainbow trout (<em>Oncorhynchus Mykiss </em>Walbaum) reared at low water temperature on a private farm, and propose preventive and control measures to prevent the recurrence of the disease and its spread to the neighboring farms or to other countries. The disease is caused by <em>Flavobacterium psychrophilum</em> and is characterized clinically by high mortality rates (25%) with necrotizing skin and fin lesions. Septicemia with muscular and gill involvement is observed in severely affected cases. The histopathological and ultrastructure alterations in the infected trout explain the pathogencity of this microorganism in many organs other than skin and fins either directly by these bacteria or by its extracellular products, or indirectly via the hypoxia and ion imbalance that results from skin and gill damage. Although some antibiotics, such as trimethoprime, chloramin T and oxytetracycline, are effective on the causative agent, improvement in water quality, vaccination, increasing fish resistance and strict hygiene as well as quarantine measures would all help.

Flavobacterium bernardetii sp. nov., a possible emerging pathogen of farmed rainbow trout (Oncorhynchus mykiss) in cold water

Aquaculture ◽  
2021 ◽  
Vol 540 ◽  
pp. 736717
Author(s):  
Izzet Burcin Saticioglu ◽  
Hilal Ay ◽  
Soner Altun ◽  
Nevzat Sahin ◽  
Muhammed Duman
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Cold Water ◽  
Emerging Pathogen ◽  
Rainbow Trout Oncorhynchus Mykiss

Cold tolerance performance of westslope cutthroat trout (Oncorhynchus clarkii lewisi) and rainbow trout (Oncorhynchus mykiss) and its potential role in influencing interspecific hybridization

2014 ◽  
Vol 92 (9) ◽  
pp. 777-784 ◽  
Author(s):  
M.M. Yau ◽  
E.B. Taylor
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Water Temperature ◽  
Cold Water ◽  
Cutthroat Trout ◽  
Acclimation Temperature ◽  
Westslope Cutthroat Trout ◽  
Oncorhynchus Clarkii ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Differential Adaptation

Hybridization between rainbow trout (Oncorhynchus mykiss (Walbaum, 1792)) and westslope cutthroat trout (Oncorhynchus clarkii lewisi (Girard, 1856)) occurs commonly when rainbow trout are introduced into the range of westslope cutthroat trout. Typically, hybridization is most common in warmer, lower elevation habitats, but much less common in colder, higher elevation habitats. We assessed the tolerance to cold water temperature (i.e., critical thermal minimum, CTMin) in juvenile rainbow trout and westslope cutthroat trout to test the hypothesis that westslope cutthroat trout better tolerate low water temperature, which may explain the lower prevalence of rainbow trout and interspecific hybrids in higher elevation, cold-water habitats (i.e., the “elevation refuge hypothesis”). All fish had significantly lower CTMin values (i.e., were better able to tolerate low temperatures) when they were acclimated to 15 °C (mean CTMin = 1.37 °C) versus 18 °C (mean CTMin = 1.91 °C; p < 0.001). Westslope cutthroat trout tended to have lower CTMin than rainbow trout from two populations, second–generation (F2) hybrids between two rainbow trout populations, and backcrossed rainbow trout at 15 °C (cross type × acclimation temperature interaction; p = 0.018). Differential adaptation to cold water temperatures may play a role in influencing the spatial distribution of hybridization between sympatric species of trout.

scholarly journals A practical guide to unbiased quantitative morphological analyses of the gills of rainbow trout (Oncorhynchus mykiss) in ecotoxicological studies

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243462
Author(s):  
Sonja Fiedler ◽  
Hannah Wünnemann ◽  
Isabel Hofmann ◽  
Natalie Theobalt ◽  
Annette Feuchtinger ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Light Sheet ◽  
Objective Evaluation ◽  
Electron Microscopic ◽  
Experimental Animals ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Aquatic Pollutants ◽  
Broad Variety ◽  
Gill Lamellae

Rainbow trout (Oncorhynchus mykiss) are frequently used as experimental animals in ecotoxicological studies, in which they are experimentally exposed to defined concentrations of test substances, such as heavy metals, pesticides, or pharmaceuticals. Following exposure to a broad variety of aquatic pollutants, early morphologically detectable toxic effects often manifest in alterations of the gills. Suitable methods for an accurate and unbiased quantitative characterization of the type and the extent of morphological gill alterations are therefore essential prerequisites for recognition, objective evaluation and comparison of the severity of gill lesions. The aim of the present guidelines is to provide practicable, standardized and detailed protocols for the application of unbiased quantitative stereological analyses of relevant morphological parameters of the gills of rainbow trout. These gill parameters inter alia include the total volume of the primary and secondary gill lamellae, the surface area of the secondary gill lamellae epithelium (i.e., the respiratory surface) and the thickness of the diffusion barrier. The featured protocols are adapted to fish of frequently used body size classes (300–2000 g). They include well-established, conventional sampling methods, probes and test systems for unbiased quantitative stereological analyses of light- and electron microscopic 2-D gill sections, as well as the application of modern 3-D light sheet fluorescence microscopy (LSFM) of optically cleared gill samples as an innovative, fast and efficient quantitative morphological analysis approach. The methods shown here provide a basis for standardized and representative state-of-the-art quantitative morphological analyses of trout gills, ensuring the unbiasedness and reproducibility, as well as the intra- and inter-study comparability of analyses results. Their broad implementation will therefore significantly contribute to the reliable identification of no observed effect concentration (NOEC) limits in ecotoxicological studies and, moreover, to limit the number of experimental animals by reduction of unnecessary repetition of experiments.

scholarly journals Emerging trends of rainbow trout (Oncorhynchus mykiss) aquaculture in Nepal Himalaya

2014 ◽  
Vol 4 (1) ◽  
pp. 7-15
Author(s):  
Tek Bahadur Gurung ◽  
Suresh Kumar Wagle ◽  
Agni Prasad Nepal ◽  
Gopal Prasad Lamsal
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Urban Areas ◽  
Cold Water ◽  
Nepal Himalaya ◽  
Nutritional Security ◽  
Mountainous Regions ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Emerging Trends ◽  
Food And Nutritional Security

Recently, aquaculture technology of cold water Rainbow trout (Oncorhynchus mykiss) has been popular among farmers in hills and mountains of Nepal Himalaya.  Production of rainbow trout started in government and private farms in 1995 and 1998, respectively. At present the rainbow trout farming has expanded in several mountain districts with rapidly growing demand in others adjacent areas.  The total farmers have increased from none to 85 producing more than 180 metric ton from 16 districts by employing about 550 people in year 2012. The trout aquaculture technology could be expanded in areas having pristine, cold and clean water resources having road access for market destinations close to urban areas of all Trans Himalayan countries as a means to food and nutritional security, and employment opportunities in mountainous regions.

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