Primorsky Aquarium reveals the world's most elusive tree frogs

The Primorsky Aquarium in Vladivostok is home to five rare species of Theloderma frogs, also called hole-in-the-tree frogs. These tiny amphibians are so well camouflaged that even experts struggle to spot them in the wild. Their ability to blend into moss, bark, and rock makes them nearly invisible—even to trained eyes. Theloderma frogs measure just 1.5 to 4 centimetres long, but their rough, textured skin mimics bark, lichen, or even bird droppings. They spend most of their time hidden in tree hollows, rock crevices, and damp cavities, rarely venturing into the open. Their webbing allows them to glide between branches and swim with surprising agility.

Finding one in the wild is a challenge. Even specialists can take a full year to locate a single frog. Dmitry Serkov, a seasoned expert, spent two years searching for one despite knowing they were present. The aquarium currently houses five species: marbled, starry, Chuangxi, Vietnamese, and brick-red. These frogs are now part of an educational project called *Growing Up in the Aquarium*, where children interact with them in one-on-one sessions.

The Theloderma frogs at Primorsky Aquarium continue to fascinate visitors and researchers alike. Their extraordinary camouflage and elusive nature make them a rare sight, even in controlled environments. The educational project ensures that younger generations can learn about these unique amphibians up close.