First report of trichodinid ciliated parasite, trichodina cobitis lom, 1961 (ciliophora: trichodinidae) from ranaghat, west bengal, infecting snakehead fish, channa striata (bloch, 1793)

Background: Trichodinids are the most common protozoan ciliated parasites which are commonly found in aquatic environments behaving as symbionts or parasites of a variety of aquatic vertebrates and invertebrates especially fishes. They are found as ectoparasites of both freshwater and marine fishes infesting the gills, skin and fins of the fishes. Species of trichodinids cause serious disease in fishes known as trichodiniasis. Objective: Trichodinids are well identified mainly based on two features- the morphology of denticles and the development of adoral ciliary spiral. The objective of this study is to identify and describe the morpho-taxonomy of the trichodinid ciliated parasites found from different host fishes and from different geographical locations. Method: During the survey of trichodinid ciliated parasites in Ranaghat, West Bengal one species of genus Trichodina Ehrenberg, 1830 namely, Trichodina cobitis Lom, 1961 was found in the gills of snakehead fish, Channa striata Bloch, 1793 from November, 2024 to March, 2025. The fishes were collected from Ranaghat fish markets and were identified by using silver impregnation method. Result: The parasite has been reported from this geographic region for the first time. This paper provides morphological and taxonomic description of the parasite based on Klein’s dry silver impregnation technique. Conclusion: Morphological characteristics of that species are confirmed by providing comparative descriptions of the morphological characteristics given by the previous authors. This study adds new host fish and new geographical distribution of the parasite Channa striata Bloch, 1793.