A classic pairing that works because they ignore each other
Angelfish can live safely with corydoras because the two species occupy different floors of the tank and have no quarrel worth having. Corydoras are small, social catfish that spend their day shuffling along the substrate in a loose shoal, sifting sand for food. Angelfish rule the open middle water and direct their attitude at other midwater fish, not at a busy group of catfish underfoot. The pairing has been kept successfully for decades, and its few failure points are husbandry details, a lonely cory, food that never sinks, or a juvenile small enough for a big angel to treat as a snack, rather than any clash of temperament.
Corydoras are a group fish, and the angels benefit too
Keep corydoras in a group of at least six of the same species, because a proper shoal feeds boldly and behaves naturally in a way a pair never does. A confident cory group works the whole bottom, including under the angelfish, and the angels quickly learn the catfish are furniture rather than rivals. Solitary or paired corys hide, eat poorly, and stress easily, which can look like an angelfish problem when it is really a numbers problem. Choose a mid-sized cory species for an angelfish tank rather than the tiny pygmy types, since body size is the simplest insurance against a large angel's curiosity.
Sand, sinking food, and the corydoras bottom routine
Set the bottom up for corydoras with smooth sand rather than sharp gravel, because corys push their barbels into the substrate all day and coarse edges wear those sensory whiskers down. Angels do not care about the substrate, so sand costs the pairing nothing and gives the catfish their natural sifting behaviour. Feed the corys deliberately with sinking pellets or wafers dropped in after the angels have had their fill, ideally some of it toward dusk, since angels snatch food from the surface and midwater with ease and will happily eat a second dinner meant for the bottom.
Size and spawning, the two moments to manage
Manage the size gap when introducing corydoras to adult angelfish, because an angel that can fit a small fish in its mouth may eventually try. Add corys that are grown or close to it, introduce them while the angels are young if you are stocking a new tank, and provide plants and low cover at the bottom so new catfish can settle out of sight. The second moment is an angelfish spawn: a breeding pair claims a vertical territory in the middle levels, and while corys underneath are usually tolerated, eggs laid low on a plant or the glass can draw the angels' defence down to the bottom for a few days.
A shared routine keeps the pairing peaceful
Keep the peace long-term by making the corys' share of the routine explicit, because bottom feeders are the fish most often forgotten by anyone covering a feeding. Note the cory group size, the sinking food they get, and the sand-sifting behaviour that tells a helper they are settled, alongside the angels' own feeding and spawning notes. Sharing both species' profiles and care details through KinsLe's Family Sharing means everyone who feeds the tank works from the same page, and the quiet catfish at the bottom get their dinner even when their usual keeper is away.