You clean algae off glass without stressing clown killifish by defending the surface first: the lid stays nearly closed, the pad is small, and every stroke happens slowly just under the waterline. Clown killifish are surface specialists that hover beneath floating plants and can jump through gaps that look far too small, so in this tank the cleaning risk is not the pad at all — it is the open lid and the torn-up floating cover.
Treat the Lid as Part of the Cleaning Tool
Open the lid only a hand's width when cleaning a clown killifish tank, because a startled killifish aims upward and a fully open top during a noisy cleaning session is an invitation. Slide a feeding hatch or lift one corner rather than removing the whole cover, work through that gap, and close it the moment your hand comes out. If the tank's design forces a fully open top, drape a towel or fine mesh over the half you are not cleaning. Make this automatic even on calm days: the one session where a fish spooks at a dropped pad is the session the habit saves it.
A Small Pad for a Shallow Working Band
The algae that matters in a clown killifish tank grows in a shallow band at and just below the waterline, where light is strongest and where the fish themselves cruise. A small soft pad suits that band better than a big scraper, letting you work in short, controlled strokes without levering against the floating plants. Move the pad parallel to the surface rather than plunging it up and down, since vertical plunging churns the calm top layer these fish require. Below that band the glass can wait for a less frequent pass; clown killifish live in the top few inches, and that is where your care should concentrate.
Work Around the Floating Plants, Not Through Them
Floating plants are shelter, shade, and egg-laying cover for clown killifish, so a cleaning session that rips them loose stresses the group long after the glass is clear. Ease the pad under the plant mat's edge rather than dragging it through the roots, and if plants pile up against the pane you are cleaning, coax them aside with the back of your hand in slow motion. Trimming an overgrown mat belongs to a separate, unhurried session — combining a plant teardown with glass cleaning doubles the disturbance, and killifish that lose their cover go pale and stop displaying for days.
Choose a Quiet Moment of the Day
Timing decides how a clown killifish group experiences cleaning, because at feeding time the whole group crowds the surface exactly where you need to work, competing and skittish. Mid-morning, when the fish have fed and settled into the plant shade, the surface band is emptier and the group is at its calmest. Clean then, in steady light, and avoid sessions right after a water change or any other disturbance.
Expect the Group to Hide, and Let Them
Clown killifish will slide into the plants when the pad appears, and that hiding is healthy, not a problem to fix by cleaning faster. Give them a minute after each few strokes, let a bold fish or two drift back out, and finish the session while some cover still holds a hiding fish or two — chasing a perfect pane by working until every fish has fled and returned repeatedly just extends the stress. If the group does not resume its surface cruising within an hour or so of a session, the next clean should be shorter, slower, and through a smaller lid gap.
Putting the near-closed-lid method into KinsLe Care Teams means a helper's cleaning session never leaves your killifish an open sky to jump at.