Water is usually neutral with a ph of 7. Acid rain causes an aquatic environment to have a low pH when the soil cannot buffer the acid rain enough to neutralize it. The groundwater eventually travels to streams and lakes and because of its acidic pH, this causes aluminum to leach out of the soil and into the water. Low pH coupled with aluminum is very toxic to many fish species and can cause low weight, reproductive failure or even species extinction. Some organisms can tolerate a lower pH while others cannot. This can lead to fish kills.The acid can lead to stress on the fish and it can stunt their growth. If the water is too acidic, the eggs may not hatch at all. Acid lowers sodium in the blood and it affects how much oxygen is in the tissues. It can affect the workings of fish gills. Lower down in the food chain, acid can affect insects that fish feed on, thus the entire food chain may collapse.