Check One: Does the Food Reach the Bottom and the School Reach the Food?
Make the first corydoras feeding check about delivery, because this school eats only what survives the trip down. Watch the sinking food land on open sand where the group rests, then watch the school converge, shoulder to shoulder, barbels sweeping the wafer as they feed. Every known member should arrive within a few minutes; a corydoras that stays parked under the wood while the others eat is the day's finding. If mid-water tankmates intercept most of the food before it lands, that is also a check result, and the fix is feeding after lights dim or dropping food closer to the school's corner, not simply adding more.
Check Two: Barbels, Fins, and Who Is Missing From the Group
Inspect barbels while the corydoras are busy feeding, because the school is still, close together, and lit from above at exactly this moment. Healthy barbels are full-length, flexible, and actively combing the sand; shortened, stiff, or reddened barbels point to substrate or water irritation building over time. Run a head count against your known school size and check fins for tears or a clamped, tucked look. Look along the flanks for pale patches or a dull film. One fish consistently last to the food and thinnest along the back is worth a written note today, since gradual fading is how this species usually declines.
Check Three: Breathing and the Surface-Gulp Pattern
Judge corydoras breathing against the species' own normal, because an occasional dash to the surface for a gulp of air is ordinary corydoras behavior, not distress. The pattern to catch is frequency: repeated trips by several fish, rapid gill movement while resting on the sand, or the whole school hovering higher in the water than usual. Those signs point first to oxygen or waste, especially on warm days or after a missed cleaning, and they deserve a water test the same evening. Compare with yesterday rather than with a generic idea of calm; a school slightly more restless each day is telling a story in installments.
Check Four: Yesterday's Leftovers and the Sand Surface
Finish the corydoras round looking down at the sand, because the substrate keeps the receipts of your feeding accuracy. Uneaten wafer fragments softening into the surface, dark waste collecting in the resting corner, or food trapped under wood all mean portions or placement need adjusting, and leftovers should be lifted out with a small siphon or baster now. Check that resting areas stay clear and that the filter outflow has not weakened, since flow drives the oxygen this bottom school depends on. A quick glance at the thermometer completes the circuit; sand, food, flow, and temperature checked in under two minutes.
When a Feeding Check Needs Same-Day Action
Escalate when the corydoras signs arrive together, because this hardy school fish tends to look fine until several small things align. Barbels visibly shorter than last week, two or more fish skipping food, or group-wide rapid breathing should trigger a water test, a surface siphon of the sand, and stronger surface agitation that day. A single fish isolating and refusing food across two feedings moves it from note to action: closer observation in a quiet tank if one is available. If the school keeps declining after water readings come back clean and the substrate is fresh, an aquatic veterinarian should examine a fish rather than the owner treating the whole tank on suspicion.
Sharing an Evening Check Without Losing the Thread
Anchor the corydoras check to the evening feeding, because that is when this school performs its whole health display at once: arrival, barbels, breathing, and leftovers. The circuit runs food lands, school gathers, barbels sweep, gulps stay occasional, sand stays clean, in about two minutes. Note the exceptions only, such as a fish missing from the group or barbels looking shorter, since a line written today is what makes next month's comparison possible. Evening feeding often rotates between whoever is home, and KinsLe Care Teams keeps that rotation honest by assigning the corydoras check to a family member or helper and stamping each finished round with a timestamp.