This is a Strawberry Poison Frog (Oophaga pumilio, previously: Dendrobates pumilio). It is a common small poison dart frog native to; Nicaragua, Costa Rica and Panama. They are also known as Strawberry Poison-dart Frog, Nicaraguan Blue Jean Dart Frog, Blue Jean Dart Frog, or Blue Jean Frog. This frog is famous because it has at least fifteen color forms, that are presumed to be mostly natural forms, and not forms caused by breeder manipulation. The genus name Oophaga means egg eater.
