Subclass Dipnoi is a group of prehistoric fish popularly known as lungfish. Lungfish are unique in their ability to breathe both underwater and in air. This subclass includes three families: Lepidosirenidae, Ceratodontidae, and Protopteridae. While these are the official scientific names for the families, they are not commonly used. Instead, lungfish are often referred to simply as "lobe-finned fish," due to their fleshy, lobed fins. Additionally, anglers and fishers may refer to them as "mudfish" or "eel-tailed catfish." However, these terms can also refer to other types of fish, so it is important to use the scientific name when discussing Subclass Dipnoi.