Criminals poisoned to death fish worth Tk 2 lakh at Alishakur village in Sreemangal upazila on Saturday.
Locals said victim Sahab Uddin, a fish farmer of the area, released fry of different variety of fish in a pond seven months ago.
Informed by locals, Sahab went to the pond and found hundreds of dead fish fry floating on the water.
On information, Sub-inspector Fazle Rabbi of Sreemangal Police Station visited the spot.
There was a longstanding conflict between Sahab and his neighbour Rasel Mia over of a piece of disputed land, said villagers.