Ishikawa's Frog: Japan’s Most Beautiful Frog

Hidden within the subtropical forests of northern Okinawa Island, the Ishikawa’s Frog (Odorrana ishikawae) is often hailed as Japan’s most beautiful amphibian—and for good reason. With its emerald-green and black mottled skin that mimics the texture of moss-covered stone, it is a true jewel of the Ryukyu Archipelago. Endemic to Okinawa, this rare and elusive species can only be found in pristine mountain streams. Some scientists suggest they are best observed above 200 meters in elevation, where the forest canopy provides the cool, humid microclimate it needs to survive. That said I've seen them at very low altitudes where if it was uncomfortable for them I'm sure they wouldn't have been there? The Ishikawa’s Frog is relatively large, reaching lengths of up to 10 cm, and is nocturnal, emerging at night to hunt insects and other small invertebrates.

A young Ishikawa's Frog in the Green morph. This is the standard aesthetic of Japan's Most Beautiful Frog

Despite its striking appearance, the Ishikawa’s Frog is a species under threat. It is currently listed as Endangered on the IUCN Red List due to habitat loss caused by deforestation, river modification, and expanding infrastructure development. Breeding occurs during the cooler months, typically from December to March, when the males emit a soft call near slow-moving stream pools to attract females. Their eggs are laid in water, and the tadpoles take several months to metamorphose into froglets. Conservation efforts are ongoing, but due to its limited range and sensitivity to environmental changes, the species remains vulnerable to human activity and climate change.

Adding to its mystique is the rare and mesmerizing Blue morph of the Ishikawa’s Frog. Unlike the typical green-and-black coloration, the Blue morph exhibits a vivid sapphire-blue in place of the green, caused by a genetic anomaly affecting the frog’s pigmentation. This phenomenon is the result of a deficiency or alteration in the yellow pigment layer, which when missing, reveals the underlying structural blue. While not common, Blue morph individuals occasionally appear in isolated populations, creating a sensation among researchers and photographers alike. These color variants are not only a marvel of natural diversity but also an indicator of the complex genetic tapestry within this island-endemic species.

Ishikawa's Frog calling during mating season: