The Marsh Frog (Pelophylax ridibundus) is native to most of continental Europe and parts of Asia, and has been introduced to the UK where it is now established in several locations in the south of England. It is rarely found in garden ponds. I have seen it for sale in the past, but because it is non-native it is illegal to release them into the wild, and that includes releasing them into a garden pond. The Marsh Frog is usually larger than the Common Frog and is much greener, usually with dark markings. It has a much louder croak than the common frog, and prominent vocal sacs on its cheeks. Marsh frogs spend much more time in water than common frogs and will sometimes feed underwater and eat small fish.
Its breeding habits are similar to the common frog. It sometimes breeds in lakes and rivers.