One pane, slow strokes, starting away from the fish
Algae comes off tank glass without stressing angelfish when you clean one pane at a time, in slow vertical strokes, starting on the side farthest from where the fish are holding. Angelfish are tall, deliberate cichlids that watch everything, defend a chosen area, and read a fast-moving scraper or a plunging hand as a rival or predator entering their territory. The technique that keeps them calm is unhurried movement they can track, in water they do not have to flee.
Let the angelfish see the tool enter slowly at a top corner. A fish that approaches, fins relaxed, has accepted it; one that darkens or retreats is asking you to pause, and honouring that pause is the whole method.
Magnetic cleaner or long-handled pad, not a bare hand
For angelfish, the tool matters because your hand inside the tank is large, warm, and shadow-casting. A magnetic cleaner moved from outside keeps you out of the water entirely and lets you park the inner half on the glass between sessions so its presence becomes familiar furniture rather than a new intruder each week. Move it gradually, especially around corners, because a magnetic cleaner that jumps or snaps to the glass sends a vibration and a sudden shape change straight at the fish.
A soft pad on a long handle suits stubborn spots and silicone seams, where blades and magnets should not go. Keep strokes smooth, never scrape toward a resting angelfish at speed, and keep scrapers flat so the edge does not chatter, because chattering is exactly the flickering motion angelfish react to.
Work during the tank's normal lit hours rather than waking the fish for an early clean. Angelfish cleaned at a familiar time, in familiar light, return to their positions in moments.
Territory, pairs, and the order of the panes
Angelfish hold opinions about space, and a bonded pair with a chosen leaf or a patch of glass they have cleaned for eggs will treat a scraper in that exact spot as a direct challenge. If a pair is tending a site or has eggs or fry, skip that pane and that corner entirely until the attempt ends; the algae there costs nothing, while defending against your pad costs the pair real stress and can cost them the eggs.
Otherwise follow a fixed order: side away from the fish first, then front, then the remaining side, leaving the back glass largely alone, since its algae is grazing and a calming backdrop. Remove dislodged film with the session's water change, and keep glass work inside the normal maintenance visit rather than making it a second disturbance.
Reading the angelfish while you work
An angelfish at ease during glass cleaning holds its long fins extended, keeps its bars at normal intensity, and may follow the cleaner at a distance like a supervisor. Clamped fins, sharply darkened bars, hiding that continues after you stop, or a fish that darts and strikes the glass all mean the pace or the tool is wrong for that individual, so stop for the day and finish the remaining panes next session. Algae is patient; it will wait.
If an angelfish that was injured in a dash, or one that stops feeding and hangs in a corner after routine cleaning, does not recover by the next day, check the water and seek advice from an aquatic veterinarian or an experienced fish shop rather than assuming it is sulking. Note which pane and which tool provoked the strongest reaction, because angelfish remember, and next session can start differently. Keeping that note with the pane-by-pane glass duty in KinsLe Care Teams lets whoever cleans this tank follow the calm order and log the finished job with a timestamp.