Mollies have long been a standard freshwater tropical aquarium fish. They are excellent starter fish. They get along with most all other tropical fish. They are active. They are 'Live Bearers', which means they 'deliver' baby fish and do not lay eggs. They are fun to watch and educational for kids. These are Gold Sail Fin Mollies, although the females do not have a high dorsal fin like the males. They are between 1.5"-2" long. They will do well in larger aquariums with many different types of tropical fish, or in a 10 gal. tank with a few other tropicals. It is recommended that you have about a tablespoon of salt(non iodized) to your aquariums water to help fend off infections and disease.