Advocacy group, Friends of Rio Cobre, says it has launched an investigation to determine what caused the death of fish recently deposited into the river.

Thousands of Tilapia fingerlings were released into the river last Friday to help revive the fish population, following a recent effluent spill.

However, Friends of Rio Cobre President, Kestonard Gordon told IRIE FM news that some of the recently deposited fish died.

Mr Gordon said the advocacy group has reached out to the National Fisheries Authority seeking answers.