Why do saltwater fish die when put in freshwater? And how long will it take for them to die?

Question

And vice versa (fresh to salt). So i expect 4 answers here =D

Answer 1

To be able to live, all living organisms must have a determined concentration of salts in the water that makes them up. For a whole bunch of biochemical reasons.
This concentration varies between organisms, but in general terms it can't be too low nor too high.
On the other hand, water moves from places where the concentration of osmolites (like salts) is low to the places where this concentration is high (a process called osmosis)
Sea water has a much higher concentration of salts than that required by the fish. So they have special celular pumps to expel the salts out of their body, back in the water. Additionally they have mechanisms of keeping the water inside (since, by osmosis, their cellular water will tend to go out)
Freshwater fishes do the opposite, since freshwater has too low a concentration of salts. (they pump salts inside their cells, and excess water out of their bodies)
These mechanisms are not reversible. So when you put a freshwater fish in saltwater, it will fill up with salts and dehydrate very rapidly. The opposite will happen to the saltwater fish in freshwater (it will be devoid of salts and its tissues will bloat with all the water coming in by osmosis)

I think death should be pretty fast, although I've never tried

Answer 2

Some salt water fish do Ok in fresh water, and many fresh water fish do well in salt, but it depends largely on the species, and how slow the change from fresh to salt or vice versa. If you take a fish direct from salt water and plunk him in fresh (or vice versa), it will probably die from shock, but gradual changes may be Ok. Many fish, like mullet or goldfish do well in either climate, so long as the change is not abrupt, and also do some research on brackish water fish.

Also sea salt is a good remedy for many fresh water aquariums (2 Tbsps per gallon), works much better than any of the chemicals they sell in pet stores.

Answer 3

Peetr is correct. And the bath times will vary on species as well, and some instead of a "freshwater" or "saltwater" bath will have a hypo or hyper salinity bath (lower or higher salinity than normal but not the complete opposite of their normal conditions). A molly can be acclimated to saltwater and live forever in saltwater. A goldfish usually doesn't last more than an hour or two tops. Some cichlids can last a day or two.

Answer 4

salt water and fresh water are totally different, lol
Put a salt water creature in freshwater, and it will die within hours, vice versa
You couldnt put a pyranahia fish in salt water, but it will live in regular( drinking) water

Answer 5

ya salt water fish will die in fresh water and vise versa
but normally there are certains species of fish which can survive in both waters,,,,,,,,

salt water fish will die in fresh water due to bursting of cells
fresh water fish will die in salt water due to loss of water from cells

Answer 6

why do you want to know?