Wild fish can carry disease or parasites, but hopefully the collector and importer (and perhaps a distributer) should have hopefully weeded out most of the carriers. You should quarantine just like you would with any fish from a different source (though we all don't do this as often as we should and many don't have issues).
As for aggression, chances are that it's a little more assertive than a typical tank raised fish. It did presumably have to survive in the wild for some time. I wouldn't worry about it too much though unless you're trying to put it in a little tank. Like RegalBlue said, rockwork and proper stocking in a responsibly-sized tank, and it should be alright.
