Shorten the nightly climb
An elderly green tree frog still climbs after dark, but his jumps land less precisely and his grip tires sooner. Rearrange his plants so broad, sturdy leaves form a staircase of resting spots from the floor to one comfortable mid-height perch, and retire the thin, whippy stems he once launched from. A thick horizontal branch wrapped partway in soft plant cover gives his feet a secure, wide hold for sleeping through the day. Keep the top of the enclosure planted but make nothing essential — water, shelter, the best sleeping leaf — reachable only by the longest climb.
Put the soaking bowl on his route, not across the tank
An elderly green tree frog soaks to hydrate, and he will soak more reliably if his wide, shallow bowl sits directly under or beside his usual descent path at night. Sink the bowl so its rim is nearly level with the substrate, and keep the water clean and conditioned, changed often, because senior amphibian skin absorbs its surroundings readily. A gentle ramp of cork or a leaning broad leaf into the bowl removes the last awkward hop. If he starts sleeping beside the bowl rather than up on his leaf, that new habit itself is worth noting.
Feed him where he already waits
An elderly green tree frog hunts by patience, sitting where prey passes, so bring the prey to his ambush spot: offer insects by soft tongs or release them onto the broad leaf below his perch rather than scattering them through the whole enclosure. Smaller insects, offered a little more often, suit a slower senior digestion and let you confirm he actually ate. Watch his aim on the first few strikes each night; a frog who repeatedly lunges short or gives up after one miss is showing you fatigue or fading vision. Feed earlier in his active period, while his energy is highest.
Keep nights calm and humidity even
An elderly green tree frog startles at vibration and bright sudden light, so move his enclosure away from television glare and late-night foot traffic if you can, and keep his day-night light cycle boringly regular. Mist in the evening to raise humidity for his active hours, aiming for even moisture rather than a soaked enclosure, and ensure ventilation keeps the air fresh around his sleeping leaf. Avoid handling him for checks; dry human hands damage the moist skin he breathes through, and an old frog recovers from that stress slowly. Judge his condition by posture, eye brightness, and nightly activity instead.
Know the senior changes that need a vet
An elderly green tree frog who stops climbing entirely, sits on the floor through the day, or leaves his soaking bowl unused for several nights is outside normal slowing down. Skin that looks dry or discolored, a bloated belly, or eyes that stay cloudy outside of shedding all warrant an amphibian vet, urgently if he stops eating altogether. Arrive with dates: when the climbing stopped, how feeding has changed, what his misting and water routine is. Assembling those notes ahead of time in his KinsLe Pet Passport turns a vague worry about an old frog into a history a vet can act on.