In conclusion, the cause of fish deaths in Lake Ranau was the release of H2S sulfur gas into the water.
As a result, there is a change in the lake's water balance system.
Previously, the phenomenon of sudden fish death also occurred in Lake Maninjau, Agam Regency, West Sumatra, in February 2022.
This event was triggered by the phenomenon of sulfur tubos, which caused the oxygen in the volcanic lake to decrease. (*)