Question: What Does the Word Tropical Mean?
Answer: The term refers to any fish that originates from waters lying between the Tropic of Cancer and the Tropic of Capricorn, especially freshwater species imported for ornamental aquariums.
Tropical fish may be freshwater or saltwater, and can belong to a variety of families. The primary factor they have in common beyond their region of origin, is the fact that they come from warm rather than cold waters. In the aquarium trade the term is often used to refer to virtually any fish kept in an aquarium.More Freshwater Aquariums Q&A