Fish species which inhabits only the freshwater
environments may be extinct in the coastal areas
due to saltwater intrusion and increase of the salinity.
As compared to terrestrial inhabitants, fish
and other aquatic creatures are subject to a
broader variety of stressors because their homeostatic
mechanisms are highly dependent on prevailing
conditions in their immediate surroundings.
Examples of additional stressors for aquatic
animals other than terrestrial animals include
fluctuations in water salinity, pH, hardness, alkalinity,
dissolved solids, water level or current,
and exposure to waterborne pathogens or toxicants.
Being an aquatic animal the fish have to
face various stressors and have to cope with regular
and unexpected fluctuation of different water
parameters to survive, and adapt physiologically
with alteration and modification of different organs
and its behavior (Jasmin, 2013).