Due to years of pollution caused by sewage and waste, hundreds of fishes are dying in the toxic water of Banani Lake, where some 16 people have been farming Pangash fish.
Over 100 fishes are dying every day for the last one month, said the fish farmers, who jointly leased the 40-acre enclosure last year and started rearing 70,000 Pangas fish.
All fishes are gradually contracting diseases that are causing them to rot and die, they said.
Unable to contain the contamination or clean the highly polluted water, the local farmers are staring at massive losses.
"All sorts of wastes from the surrounding sewer lines end up here causing the lake water to become more dirty and poisonous by the day," said Jabbar Hawladar, one of the lessees.
On the east side of the lake is Godown slum, which was formed by occupying the lake. Four pipelines run underneath the slum and two of those are clogged, due to which water flow is disrupted.
"Besides, people dump their garbage here causing it to turn toxic," Jabbar added.
"Speaking with doctors we came to know that fishes have caught insects and lice due to excessive contamination of the water," Mohammad Ripon Kajal, another lessee told The Business Standard.
"To stop the contamination, we have spent more than Tk12 lakh so far but to no avail," said Kajal.
He went on to say that as there is a real chance people may become sick from consuming infected fishes, they are not selling the remaining ones in good conscience.
Shafiqul Islam (50), a local resident, told The Business Standard that the late Mayor Anisul Huq planned to bring the lake under the Hatirjheel project, but after his death no progress has been made in this regard.
Shafiqul Islam also said that the lake was in a dilapidated condition due to land grabbing, mismanagement and lack of supervision.
"At present, it is difficult to stand near the lake due to the pungent smell," he said adding, "Mosquito infestation has also increased in the polluted water and various diseases are spreading."
Poribesh Bachao Andolon (Poba), an organisation that promotes environmental protection, has observed that household waste from Banani, Gulshan, Baridhara, Badda, Kalachandpur areas and waste from construction works are dumped in the lake.
Besides, there is no central sewage management system in Banani, Gulshan, Baridhara, Badda and Kalachandpur areas prompting people living nearby to dump waste in the lake.
The organisation warned that the polluted toxic water of the lakes poses a serious threat for the environment, public health and biodiversity.
Abu Naser Khan, chairman of Poba told The Business Standard, "Authorities should immediately make biological management of the lake as well as prevent waste dumping and illegal occupation."
Asked on illegal land grabbing on the lake, Dhaka North City Corporation ward 19 councillor Md Mofizur Rahman told TBS, "We are listing names and the area of illegally occupied lands. There is also a plan to evict them with the help of the mayor."
He added that repair work of the pipelines at the Godown slum area is set to begin soon.