Small fish, quiet old age
A panda corydoras in its senior years looks much like it always did — cream body, dark eye patch, that saddle of black — but the tempo changes. Foraging bouts across the sand grow shorter, rests tucked against plants or under a leaf grow longer, and the mad dash to the surface for a gulp of air happens a little less often, though it never disappears entirely. Pandas are a comparatively delicate corydoras, less forgiving of warm, stale, or rough conditions than their hardier cousins, so old age in this species is mostly about removing small frictions before they add up.
Sand is a medical issue, not a style choice
Those barbels — the whiskers it tastes the floor with — wear down on sharp gravel, and an older panda has less ability to compensate for damaged ones. Smooth sand it can sift is the kindest floor for a senior, and if your tank runs gravel, at least keep it rounded, clean, and free of the mulm that collects between stones, because a grubby bottom is where barbel erosion and infection start. Check the barbels weekly at feeding time: they should look full-length and clean. Shortening, redness, or a fish that stops sifting and only hovers are findings to note with dates, not to watch indefinitely.
Feed the floor like you mean it
Most senior pandas do not starve from lack of food in the tank; they starve from lack of food on the floor. Midwater fish intercept flakes and pellets long before anything sinks, and an old cory that arrives slowly finds crumbs. Feed a dedicated sinking portion sized for the bottom-dwellers once the main community feed is underway, placing small softened wafers or granules in the pandas' usual corner, and consider a lights-dim feed when the group is most active. Verify with your own eyes that the senior is eating — a rounded belly line after feeds is the evidence you want.
Company, warmth, and steady water
Keep the school together; panda corydoras are group fish, and a lone senior fades quickly. Numbers matter more than new additions of other species. Hold temperature in the cooler, comfortable part of this species' range and keep it steady, since pandas feel heat and oxygen dips sooner than most tankmates, and old fish feel them soonest of all. Gentle, regular water changes with careful attention to the bottom layers suit them better than heroic occasional clean-outs that stir the substrate they live on into the water column.
Small signs, early action
Seek advice from an aquatic veterinarian if a panda stops foraging entirely, if barbels erode despite a clean soft floor, if breathing stays rapid at rest, or if the fish separates from the group and sits in the open — prey fish hide weakness, so a cory behaving oddly in plain view is usually well past the first stage of a problem. Dated notes on barbels, appetite, group size, and water readings in KinsLe's Pet Passport give this two-inch fish a senior record as careful as any large pet's, which is exactly what early action depends on.