I keep tropical at the moment because im a beginner and marine seems alot harder, tropical tanks can be amazing but I think marine is my favourite the fish and coral look stunning but until im alot more experianced Il stick to tropical
Right now I am thoroughly enjoying my goodeids. They are not tropicals and unlike some comments in this thread about cooler water fish they are not giants that need huge tanks. They are subtropical and can often be kept in good health down to less than 50F, 10C. I guess they would be called freshwater by the odd classification system you are using.