The Fisheries Department are trying to combat the problem by spreading lime and dolomite, but have not been able to say how many fish have been killed.
Almost 10,000 hectares of crops are rotting in three haors, district fisheries official AKM Shafiquzzaman toldbdnews24.com.
Six tonnes of lime and dolomite have been spread to curb the problem, he said. Fish spawn will also be introduced to replenish local stocks.
Juri Upazila fisheries official Md Abdus Sakur says fishing has also been barred in the area for three to four days in an effort to maintain stocks.
Heavy rains are likely in the next three to four days, according to the Meteorological Department, said District agricultural official Md Shahjahan. This may cause further damage to crops.