Freshwater aquariums are enclosed tanks filled with water that house various species of fish, plants, and other aquatic life. They are popular among hobbyists due to their relatively low maintenance compared to saltwater aquariums. Common fish species include goldfish, betta fish, and neon tetras, while plants like java fern and anubias enhance the tank's aesthetic and provide oxygen. Setting up a freshwater aquarium involves selecting the right tank size, filtration system, and substrate. Proper water conditions, including temperature and pH levels, are crucial for the health of the inhabitants. Regular maintenance, such as water changes and cleaning, helps ensure a thriving aquatic environment.