A small mouth and a shy nature settle the question
Most compatibility questions are about managing risk. This one barely is. The rummy nose tetra is a small, deep-schooling fish whose whole survival strategy is staying in the middle of a tight group and fleeing anything unfamiliar. Its mouth is genuinely tiny — built for micro food drifting in the current — and an adult cherry shrimp is simply too large and too quick to register as prey. Rummies do not pick at snails, do not investigate the substrate for hidden food the way barbs do, and rarely leave the middle layer of the tank at all. If you are building a shrimp display and want one fish species to animate it, keepers reach for this tetra precisely because the pairing asks so little compromise.
Shrimplets still need their first-days cover
The single exception is the newborn shrimplet, which is at risk from almost any fish with eyes, rummies included — not from hunting, but from reflex. A two-millimetre shrimplet drifting across open water looks like a daphnia, and a rummy will take it without ever knowing it was a shrimp. The fix is the standard one and it works exceptionally well here: a cushion of moss, a thicket of fine-leaved stems, or a pile of cholla wood where the young spend their first week grazing biofilm. Because the rummies show no interest in patrolling that cover, survival out of each batch is high, and a colony in a rummy tank typically grows steadily rather than merely holding on.
Snails pass completely beneath their notice
Nerites, mystery snails, ramshorns, the hitchhikers on new plants — a rummy nose tetra treats all of them as furniture. There is no pecking at feelers, no interest in eggs, no competition worth mentioning at feeding time, since the tetras feed in the water column and the snails clean up whatever drifts down. The pairing is so neutral that the snail choice can be made purely on the tank's needs: nerites for glass algae, a mystery snail for character, trumpet snails for turning the substrate. Nothing about the fish constrains it.
The real challenge is the rummy, not the shrimp
If this pairing has a difficulty, it is keeping the tetras themselves comfortable, because a stressed rummy is a pale, skittish fish that hides behind the filter. They want a proper school — ten or more, so their famous nose-to-tail synchronised swimming actually emerges — and they want settled, warm, soft water that does not swing. Add them to a mature tank rather than a new one, acclimate them slowly, and let the shrimp colony be long established before the fish arrive; the shrimp will not notice the newcomers, but the newcomers will settle faster in a tank that already smells lived-in. Buy the school from one batch so they shoal tightly from the start.
What a settled rummy and shrimp tank looks like
Within weeks you should see the arrangement the pairing is famous for: the scarlet-nosed school sweeping the open water in unison while cherry shrimp graze the plants beneath them in full view, utterly unbothered, and juveniles appearing on the moss in growing numbers. Shrimp out grazing in the open is always the trust metric in a community tank, and with rummies it reaches its highest level. Keep the school's size, the feeding routine, and water-change notes on the tank's KinsLe Family Sharing profile, so whoever in the household feeds or tops up the tank keeps the calm conditions this pairing depends on.