author(s)
Indrani Sarkar, Tiyasa Dutta, Choudhary Soumee Sanjay, Arnab Basu, Swadhin Kumar Tarafdar and Srijit Majumdar

abstract
Fish gills are comb like structure richly supplied with blood vessels. It is the site of gaseous exchange. It plays a vital role of not only respiration but also ionic balance, osmotic balance and filtration of food. Gill rakers are associated with gills. Fishes are herbivore, omnivore or carnivorous. They filter the suspended food particles. According to their feeding habit structure of gill rakers varies. Both marine and freshwater herbivore fish longest gill racker. In our experiment highest length at gill racker observed as 950 µm in silver carp and carnivore fishes contain small minute racker even sometimes it is absent. Smallest length of a gill racker observed in Topse (Polynemus paradiseus) is 150 µm.