You don't wanna miss this video! (NOT A SPAM!)
 

Didn't want to ruin the surprise with an understandable title but...well...seeing is believing :P

http://www.youtube.com/watch?v=crLfRyf935E

Wild!!

I assume they are in brackish water. I don't know if all those fish would be happy long term. You can push any fishes normal range of salinity, you'll know you've gone too far when they die. They may not be able to breed, and it may shorten their lifespan, but you can keep fish outside their normal salinity.

We've kept fish at a salinity of 1.009 (hypo) to treat the fish for marine ich so I would imagine you could acclimate the freshwater fish to that salinity level also.

Pretty neat to see but not very practical.

Its brackish, 1.018 or something, just slow acclimation and apparently this is a temporary exhibit. I remember some company trying to sell the idea to freshwater hobbyists several years ago.. I don't think it took off.

That's exactly what I was thinking. Hypo. Brackish would be too high for goldfish, hypo sounds more believable.

Goldfish can actually tolerate salt water much better then most tropical fish. Quarantine for them they usually sit at a 0.1-0.3% salt solution, and dips are 3% (30 teaspoons per gallon) and when I did the dips on my guys daily, the more often I did them, the more they got used to them and swam around in their salt water like nothing was wrong. Probably explains why the goldfish in that video are the most active fish in that tank. Its gotta be closer to brackish Im thinking... So im leaning more towards what Marie said..

Very cool....in a freaky weird kind of way. :)

here in this video they hae trigger with bigger fw fish lol
http://www.youtube.com/watch?v=gNtcCVIbwcY

divided tank...with the gold fish at the front in freshwater and saltwater in the rear section, watch the video again and notice that the two never mix.