What happens if......

[BioFilter]

you put a salt water fish in fresh water? I dont plan on doing this and I know it will die, but how and why? Correct me if Im wrong, but I think if you put a fresh water fish in salt water, it dehydrates it and kills it.

 

[Malbri]

or it burns their skin

 

[jm1212]

water naturally moves to a hypertonic solution (a solution with more dissolved solids) from a hypotonic solution (an area of less dissolved solids concentration). therefore, a freshwater fish put into salt water will not be able to adapt and will have all of the water litteraly sucked out of its cells. salt water fish have adapted so they are able to retain water, but they will have to "drink" in water to stay hydrated. if you put a saltwater fish in straight freshwater, it wouldnt be pretty. the water would rush inside the fish and the cells would rupture.

 

[Siren]

If I remember my biology/chemistry correctly, things that are highly concentrated move to be dispersed into something less concentrated. So therefore, the salinity of their bodies would be reduced enough to mess up their internal cellular structures' ability to keep the cell functioning. Sodium/Potassium cellular exchange comes to mind....
Though, it's been a while and I could be WAY off base....

 

[Toirtis]

However, a short (2-4 minute) dip in freshwater is an accepted and usually safe way to rid marine fish of external parasites.

 

[BioFilter]

Thanks for the responses, that helped clear up what happens to sw fish in fresh water. I guess there will always be an animal that defies nature, like the salmon, who lives at sea, then enters fresh water streams to spawn. Im sure there are other species that can traverse between the two, but I dont know what they would be.