Fish cultivation in cages has come as a boon for many farmers, especially those living near open water bodies in Sadar upazila under the district.

Some enthusiastic youths are engaged in cultivating monosex tilapia in cages in the Mohananda River adjacent to Namo Rajapur, Namo Nimgachhi, Police Line, BGB Camp, Shaheber Ghat, Bhogobanpur and Horipur area in Sadar upazila.

Now over 170 floating cages in the river are used for tilapia cultivation as it is profitable due to low production cost and easy farming method.

"In 2010, seeing a newspaper write-up about fish farming in cages, I decided to be a fish farmer. I took Tk 15,000 as loan from an NGO and started fish farming in ten cages along with my seven friends the same year," said Humayun Kabir, 26, of Bhogobanpur village in Sadar upazila, who earlier worked as a mason.

"Each cage, costing Tk 5,000, lasts for years. We invested more Tk 12,000 to 13,000 per cage in a couple of months.   

"Later we started fish farming individually. Now I have 15 cages in the Mohananda River, near my house. I earned handsome money after selling fish in last few years," he said.

Shahidul Islam Mithun, 35, of the same area, invested Tk 3.5 lakh for cultivating fish in 35 cages and he makes a profit of around Tk 3 lakh after every three months.

"Seeing our success, many youths are taking to fish farming in cages," he said.

Fish cultivation in 20 cages can easily earn a farmer Tk 40,000 to 50,000 per month, said Alamgir Hossain, a farmer of Namogachhi Moholla in Chapainawabganj municipality.

Wives and other family members often help in the work, serving feed in the cages and taking care, said the farmers.

"Tilapia cultivation in cages requires a small investment and effort but brings good profit. We give required suggestion to the farmers for cultivating fish in cages," said Dr Aminul Ehsan, fisheries officer of Sadar upazila.

The cage cultivation method produced 18 tonnes of fish in 2013 and 74 tonnes in 2014 while the expected output this year is at least 150 tonnes of fish, he said.