Freshwater Fish, a vast number of species are kept in the home aquarium. Tropical Freshwater Fish require a heater in the aquarium and Coldwater fish such as Goldfish do not require a heater. All fish tanks should have a filter running. Aquarium plants can be added into the Aquarium to provide a natural home for your fish. Many species of fish are kept such as Community Fish, fish that are usually happy to live together peacefully - guppies, mollies, platys, tetras, Angelfish, Swordtails, Dwarf Cichlids. For the larger fish tank Oscars, Puffer Fish, Cichlids. Fish that help clean the aquarium are always welcomed Plecos, otocinclus, and numerous species of shrimps such as cherry shrimp and amano shrimp.