How we kill our fresh water fish?
We dump or divert detergents into the rivers or the Kandy Lake!
But mosquito larvae somehow survive.
How I do not know.
Detergent affects the gills of the fish and their breathing.
Detergents can have poisonous effects in all types of aquatic life if they are present in sufficient quantities, and this includes the biodegradable detergents. All detergents destroy the external mucus layers that protect the fish from bacteria and parasites; plus they can cause severe damage to the gills.
Most fish will die when detergent concentrations approach 15 parts per million. Detergent concentrations as low as 5 ppm will kill fish eggs. Surfactant detergents are implicated in decreasing the breeding ability of aquatic organisms.