What is the difference of freshwater fish and marine fish?

* Habitat: Freshwater fish live in bodies of water with a salinity of less than 1 part per thousand, such as rivers, lakes, and ponds.

* Osmotic regulation: Freshwater fish are hypo-osmotic to their environment, meaning that they have a lower concentration of solutes in their body fluids than in the water around them.

* Chloride cells: Freshwater fish have chloride cells in their gills that help them absorb chloride ions from the water and excrete bicarbonate ions.

Marine Fish

* Habitat: Marine fish live in bodies of water with a salinity of 35 parts per thousand, such as oceans and estuaries.

* Osmotic regulation: Marine fish are iso-osmotic to their environment, meaning that they have the same concentration of solutes in their body fluids as in the water around them.

* Salt glands: Marine fish have salt glands in their gills that help them excrete excess salt from their body fluids.

In addition to these physiological differences, freshwater fish and marine fish also differ in their anatomy, behavior, and reproduction.