Theophanes says
Generally no, but that being said there are exceptions. Salmon for instance hatch in fresh water streams and rivers, wash out to sea, live their lives, and return to the rivers to spawn before dying. Bull sharks have been reported (very rarely) as far as 40 miles inland... but for the most part salt water is usually deadly to fresh water fish and salt water fish have evolved to need salt so a fresh water enviroment can't be sustainable to them for very long (eventually those sharks have to go back to sea or die.)
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