Almost 200 tons of Brazilian menhaden were collected in four days in early March in the Río de la Plata, and experts have not yet determined the cause of the fish's death.
Most of the dead fish were females who had laid their eggs, and sample necropsies found no evidence of infectious parasitosis, which could explain the massive death of fish.
La Dinara reported a current growth of 2 C (3.6 F) degrees in water temperature during February, a level above historical records for the region.
A study of phytoplankton has not revealed the presence of species that could produce toxins harmful to fish, the agency said.
The fact that only one species of fish seems to have been affected by the rise in mortality led Dinara specialists to rule out the possibility of the presence of contaminants in the water.
The fact that the death of fish occurred on the 2 banks of the Río de la Plata makes it "very improbable" that the cause has been waste dumped by fishing vessels, the agency said. "For these reasons, there is no risk to health from fish consumption, both in coastal and deep waters", finished the Dinara.
Blue Channel 24