Criminals poisoned cultivated fishes worth about Tk 15 lakh to death in a water body beside Patuakhali-Barisal in Khalishakhali area under Sadar upazila of the district.
On Friday morning, thousands of dead fishes were found floating on water, said fish cultivator Md Hasan, a college student.
He started fish cultivation after receiving training and released various species of fish including pangas and grass carp in the ditch two months ago, said the affected fish cultivator.
“I cultivated fish by borrowing money from relatives and taking loan from NGO,” he said.
Newly elected UP Chairman Md Lutfor Rahman Manik Miah said those who are involved in the offence must be brought to book.
A case was filed in connection with the incident, said SM Tariqul Islam, officer-in-charge of Patuakhali Police Station.
Punitive action will be taken against the culprits after investigating the incident, said the OC.