Identification of freshwater eel species of Genus Anguilla is crucial and essential in many aspects including evolutionary biology study, population genetics study, aquaculture field and others. During the species identification process, selection of a simple and accurate method with minimal requirement for resources is needed.
Here, we evaluated three approaches consisting of morphological characters, DNA-based methods (PCR-RFLP & DNA sequencing) as well as protein-based method for species identification. Evaluation of these methods was carried out based on consideration of several factors including accuracy, processing time, efficiency for large quantity testing and operating cost.
In the study, we found that identification of freshwater eel of Genus Anguilla was difficult by simply through the morphological characters due to overlapping patterns among different species. Moreover, for the protein-based approach, differentiation of closely related species was difficult due to the complexity of the protein composition in fish mucus. However, we managed to demonstrate that through the protein profile in SDS-PAGE, Anguilla japonica could be differentiated from the other three freshwater eel species namely A. marmorata, A. bicolor and A. huangi.
Genetic molecular approaches are more reliable, sensitive than the morphology-based judgement and the protein-based method as higher accuracy can be obtained even though longer processing time is needed. In the evaluation of the method based on accuracy, processing time efficiency, efficiency for large quantity testing and operating cost, the use of DNA-based methods for freshwater eel species of Genus Anguilla is more superior.

淡水鰻魚(鰻目鰻鱺科)物種之鑒定在許多領域非常重要，例如生物演化研究，遺傳學研究及水產養殖業等。在物種鑒定的過程中，選擇一個簡單，正確，資源需求低的方法是在各領域中共同需要的。
本研究將針對三種鑑定的方法：外部型態特徵比較、分子鑑定法(PCR-RFLP　和 DNA sequencing)和鰻魚黏液蛋白質電泳分析，依據以上三種方法的準確性，所需操作時間，篩選規模大小以及所需成本，進行分析及評估。
本研究的實驗結果顯示由於外部型態特徵比例有部分重疊，所以在分辨上是會造成一些錯誤的鑑定。在鰻魚黏液蛋白質的分析上，結果顯示黏液的蛋白質構成成份非常複雜，以蛋白質來分辨相似物種，並不為較有效率的方法。然而，透過一維蛋白質電泳分析，日本鰻 (Anguilla japonica)所呈現的樣式，與其他品種的鰻魚如鱸鰻(A. marmorata)，雙色鰻(A. bicolor)和黃氏鰻(A. huangi)是有所區分的。
相較於外部型態特徵與黏液蛋白質分析，分子鑑定法顯示的結果是較為可靠的。分子鑑定法需要較長的操作時間，但所呈現的準確性極高。本研究針對各方法的準確性，操作時間，篩選規模之大小以及成本評估，結果顯示分子鑑定法較其他方法更準確及有效率做出淡水鰻鱺的物種鑑定。

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