There are many types of open stream. Short description of some open stream are listed below.
Rivers are very important open stream. Large number of fish are being collected from rivers every year. It is a great source of fish production and collection. About 0.35-0.5 million metric tons fish are being produced and collected from rivers every year. Many species of fishes are collected. Among them the contribution of hilsa fish is most. The total area of rivers of Bangladesh is about 1.32 million hectors. The Padma, Meghna, Jamuna, Brommoputra etc. are big rivers of Bangladesh. Minnow of carp fish like rui, katla, mrigal are collected from rivers.
Swamp, bill, fen, bog etc. are natural stream. There are many swamp in Sylet, Moymenshing district or flooded area and many bill in Jessore, Kustia, Faridpur, Pabna, Rajshahi, Rongpur, Dinajpur, Commilla and Dhaka district. The total area of this types of land is about 0.247 million hectors. The Hakaluki swamp of Sylet is the biggest swamp of Bangladesh. A large number of fish like rui, boal and other small fish are being collected from this types of stream. This types of stream get flooded by rain water.
In Bangladesh a large number of land get flooded every year. There are about 2.833 million hector flooded paddy field. Water stays in this types of stream for 3-6 months. Flooded land helps to increase the overall production of fish. It is a great place for roaming, breeding and production of fish. About 7 million land of Bangladesh get flooded every year.
There are about no difference between lake and pond. But lakes are of big sized. Generally the pond with area of more than 10 acres is called lake or mere. Lake can be both natural and created. The Kaptai lake of Bangladesh is a artificially created lake. It is the biggest lake of south-east Asia. The area of this lake is 68,800 hectors. This lake is a great source of freshwater fish.