Corydoras lose the feeding race by design. They are bottom fish with small, down-turned mouths, built to sift the substrate in a group, while the flakes and floating foods tanks are usually fed vanish into faster mouths long before anything drifts down to them. A corydoras shoal can live in a generously fed tank and still go thin, simply because the food never arrives where they feed. The fix is not more food. It is food in the right form, delivered to the right level, at the right hour.
Food That Sinks and Lands
Feed sinking wafers and pellets made for bottom feeders, dropped so they land on the substrate in one piece rather than dissolving on the way down. Add frozen foods, thawed and placed at the bottom, as the richer part of the rotation, because corydoras are foragers who need more than algae scraps and whatever the other fish miss. Presentation matters as much as the food itself: drop the wafers in the same open patch of substrate each time, near where the group shelters under wood or plants, so the shoal learns the feeding spot and arrives together instead of hunting the whole floor for a pellet that landed behind the filter. A length of tube or a pair of long tweezers puts food exactly there, past the mid-water rush, without your hand scattering the tank. Break a wafer when the group is small, because one whole wafer left uneaten fouls the very patch of floor the corys feed from. Start with one wafer or a couple of pellets for a small shoal and adjust by what is gone by morning, which teaches the right portion faster than any packet direction.
Feed Part of It After Lights-Out
Timing is the second half of the answer. Corydoras grow bolder and more active as the light fades, while the day-active tankmates that outcompete them settle and stop hunting. So split the feeding: a modest amount with the main tank feed, and the corys' real portion after lights-out, dropped quietly onto their patch once the surface has calmed. Within a week the shoal usually learns the rhythm and is waiting at the spot. Watch what happens in the first ten minutes: food still sitting untouched in the morning means the portion was too large or the spot is wrong, while food mobbed and gone means the amount is about right. Check bellies weekly as the honest scorecard, gently rounded behind the head on a feeding cory, hollow and pinched on one that is still missing out.
Who Owns the Late Feed
A lights-out feed is the easiest job in the tank to lose, because it happens after the visible routine is done and everyone assumes someone else dropped the wafer. It survives when it belongs to a named person on a named evening rather than to the household at large. Through the Care Teams duties for this tank, one person owns the evening cory feed on their nights, drops the wafers onto the shelter patch after the lights go off, and marks the task done when it is finished, so the next person can see at a glance that the bottom food went in. When the duty rotates, the note travels with it: which patch, how much, and whether the shoal fed well, so a new helper feeds the floor and not the surface.
Kept that steady, the shoal stops watching dinner disappear overhead and starts meeting it on the floor where they live. Logged through the Care Teams rotation on KinsLe, each late feed is marked done and hollow bellies get spotted early.