The name of the biggest bill in Bangladesh is Chalan Beel (Chalan Beel). This Chalan Bill is a collection of many small bills spread across Natore , Sirajganj and Pabna districts. The island-like floating green villages in monsoons, chirping of visiting birds in winters, blue sky and the beauty of kasban forests blooming along the banks of the Beal in autumn leave the visitors mesmerized. It is only during the full monsoon that the true nature of the movement bill is detected. And then about 368 square kilometers of area became alone in water. Apart from the rainy season, many tourists flock to float on the Chalan Beel in boats or enjoy the varied beauty of the Beel almost all year round.
At one time the total area of Chalan Bill was 500 square miles or about 1424 square kilometers. However, currently the area of Chalan Bill has reduced to 1150 square kilometers. Numerous smaller bills have been added to the current bill through canals. Piprul, Laror, Dangapara, Tajpur, Nyala, Majhgaon, Chonmohan, Shatail, Darikushi, Gajna, Barabil, Sonapatila and Ghugudah are some of the names of such bills.
Several rivers including Karatoa, Atrai, Gur, Baral, Mora Baral, Tulsi, Vadai have joined the Chalan Bill. The fish-rich Chalan Beel has various species including Chital, Magur, Koi, Shing, Boal, Taki, Shoal, Mrigel, Prawn, Tengra, Kaliboush, Rita, Mousi, Gajar, Bou, Sarputi, Punti, Guja, Gagar, Baghair thorn, Titputi. the fish



