From The Aquarium Wiki
Dwarf African Frog
This small bottom dwelling frog typically stays smaller then 6.4cm (2.5") and can be kept in an aquarium of minimum 18.9 Litres (5 US G.) plus. Because of its active lifestyle and its availability in local pet stores it has been a common addition to many aquariums. Be careful not to mistake it for the African Clawed Frog!
For more details please click on the Title name.