The rosy barb outgrows its community-fish reputation
The rosy barbs in the shop tank are an inch of peachy gold and look harmless. The adult in a home aquarium is a different proposition: a deep-bodied, fast, perpetually hungry fish approaching the length of your hand, kept in a shoal that moves like a pack. That size is the whole compatibility story. A cherry shrimp that a small tetra ignores is, to an adult rosy barb, a prawn — and rosy barbs forage constantly, nosing through plants and gravel all day for exactly that kind of morsel. This is not aggression; it is appetite. Tanks that mix rosy barbs with cherry shrimp do not usually report attacks. They report that the shrimp quietly disappeared over a month.
Why even adult shrimp are at risk here
With smaller barbs, the rule is that adults survive and only the babies are eaten. Rosy barbs break that rule because their mouths keep growing. An adult cherry shrimp fits. A moulting shrimp, soft-shelled and hiding poorly while its new shell hardens, is defenceless against a fish this size. Amano shrimp are the one realistic exception: they grow larger than cherries, they are assertive feeders, and in a spacious, heavily planted tank a group of amanos can often hold territory the barbs lose interest in. Even then, expect the amanos to live warier lives than they would with small fish, and never add them to a tank where the barbs already rule an open layout.
Snails are the cleanup crew this tank can actually keep
Where shrimp fail, snails succeed. A nerite's low profile and iron grip make it untouchable, and its grazing suits a rosy barb tank, because these big eaters produce the algae growth that follows generous feeding. Mystery snails manage too, with one watch-out: rosy barbs are curious peckers, and a mystery snail's long feelers can get nipped as they wave in the current, so provide plant cover the snail can retreat into and watch that it keeps extending its feelers fully — a snail that stays shut for days is being bothered. Malaysian trumpet snails in the substrate are simply ignored. Build the cleanup plan on snails and you lose nothing the shrimp would have provided except the spectacle.
If you still want to try shrimp, stack every condition
Some keepers do run amanos with rosy barbs, and the setups that work share a pattern. The tank is large, because space dilutes encounters. The planting is jungle-dense at the back and bottom, with moss and fine-leaved thickets the barbs cannot bulldoze — and rosy barbs do bulldoze, uprooting soft stems as they forage, so anchor plants well. The shrimp go in first and grow to full size before any barb arrives, and the barbs arrive as juveniles who grow up treating the amanos as furniture rather than food. Feed the barbs a varied diet with plenty of vegetable matter, since a rosy barb short of greens turns to grazing everything else in reach, shrimp included.
Choosing between the fish and the shrimp honestly
For most people this question resolves into a fork: the rosy barbs are the display fish and the tank is stocked around them, or the shrimp colony is the point and the fish stocking stays small and gentle. Trying to have both at full strength usually ends with expensive shrimp becoming barb food and a keeper blaming the fish for doing what its size dictates. A good local aquatics shop will show you a grown rosy barb, which settles the question faster than any chart — find one through the KinsLe Pet Services Directory and look at the adult fish before you commit the shrimp.