Life at the surface, at a senior's pace
A senior clown killifish exercises in the top layer of the water and nowhere else. His activity is a slow cruise beneath the floating plants, a pause hanging in the roots, then a short dart when something edible touches the surface film. A young male covers the whole surface this way and spars with rivals along the plant line. An old male keeps to a favorite stretch of cover, darts less often, and rests in the roots for long spells between patrols. His exercise requirement shrinks to match: connected floating cover he can cruise under, and food arriving on the surface within his stretch of it.
Tiny food, delivered along his stretch of cover
Keep a senior clown killifish moving by feeding along his patrol line rather than at one point. Touch minute foods to the surface at several spots under his floating plants so each short cruise ends in a small hunt, and prefer tiny live foods that struggle briefly in the surface film, because movement overhead is what triggers his strike. His mouth is very small and upturned, and age does not enlarge it; food that suits a young killifish barely suits a senior, and anything larger is simply watched as it drifts away. Feed little and often across the day when you can, since a senior's short patrols pair naturally with small, frequent rewards.
A lid, calm surface, and no one stealing his layer
Comfort for a senior clown killifish is a surface he can trust. Keep a close-fitting lid without gaps, because these fish jump through astonishingly small openings and a startled senior jumps as blindly as any youngster. Break the filter's return so it does not ripple his cruising layer or sweep his floating plants into one corner, leaving his stretch of cover bare. Choose tankmates who live below the surface and leave his layer to him; even peaceful midwater fish that snatch floating food will quietly starve an old killifish who will not hurry. Shade from the floating canopy itself keeps his colors and confidence up.
Surface fish, surface warnings
Watch a senior clown killifish where he lives: at the top. A healthy old male still cruises his stretch and darts at food, however short the patrol. A killifish who hangs motionless in one corner of the surface, lets food touch the film beside him without striking, or sinks to midwater and stays there is showing a problem, not a preference. Test the water, check that the surface has not filmed over and dulled oxygen exchange, and make sure no new tankmate has claimed his plant line. Continued refusal of food or a thinning body in so small a fish moves fast, so involve an aquatic veterinarian early rather than after days of watching.
The routine is small, so write it exactly
Clown killifish care is a list of small exactitudes: the gap-free lid, the tiny food, the unrippled surface, the senior's own stretch of plants. Any one of them forgotten by a substitute feeder undoes the others. KinsLe's Pet Passport keeps that exact list with his records in one packet, so the old surface-dweller's quiet patrols continue undisturbed under any caretaker.