Question

Why fresh water fishes cannot survive in sea water?

Answer 1

this is because exosmosis occurs . When fresh water fish go to sea water,the sea water has higher concentration of solute ie salt and lower concentration of solvent.As we know solvent moves from its higher concentration to lower concentration.Hence Due to this water from inside of body of fish (high solvent concentration of water)moves out to sea water .Cells of body of fish shrinks and it dies.

Answer 2

Saltwater fish can live in salt water since they have always lived in it and they are able to get it out of their selves. Once the saltwater fish drink the salt for hydration, their kidneys pump the excess salt into their urine so they can get rid of it. Freshwater fish can’t get rid of the salt (if it gets into their body) because they don’t usually have it in their freshwater habitat.

When a freshwater fish touches salt water, the water comes out of them and they get dehydrated. When a saltwater fish is near or exposed to freshwater, the water flows into them filling up cells and either the cells burst, or they stop working.