Another broodfish has been found floating in the Halda River, known to be Bangladesh's largest natural breeding ground for carp.
Locals spotted the dead fish on Sunday in the river's Ajimer Ghat area in Hathazari upazila.
It is the latest in a series of carps that have been found dead in a short span of time.
It is assumed that the 4kg mrigal fish (cirrhinus mrigala) might have died after being hit by the propeller of an engine-run boat, or a sand-extracting dredger.
On April 29, locals spotted a dead mrigal carp weighing 7kg with injury marks at the river's Kumarkhali point in Uttar Madarsha union of Hathazari upazila.
On April 27, a mrigal fish weighing around 12kg was found floating on the river, and was later handed over to the Halda River Research Laboratory to determine the cause of death.
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On April 9, a mrigal weighing 8kg was found dead in the river's Khalifaghona point. Bruises were found on the body of the broodfish.
On March 4, a 12kg catla fish and a long-whiskered catfish were found floating on the river at Gorduara point.
Additionally, the survival of critically endangered dolphins is also at stake in the Halda river.
On April 16, a six-month-old dolphin with scars was found floating at Madunaghat point of the river.
To help preserve the aquatic balance, the plying of mechanized boats in the river is prohibited between March and July every year.
In 2010, the government had declared 40km of the Halda river – from Nazirhat to Kalurghat – as a sanctuary for aquatic animals.