I googled but was unable to come up with a definitive answer. I like the shape of the galvanized over rubbermaid. Would I have to do anything special to the galvanized tank to house fish?
Yep you'd have to put in a liner otherwise Eventually the galvanised will end up killing your fish , do a search on here there are a few stories about it
Galvanized is nothing more than an alloy of metals with a zinc coating that simply rusts slower than steel. It is not fish safe, and I wouldn't even use it for my livestock.....