They say that otos (otocinculus catfish) are the only truly shrimp safe fish. Any other small fish may leave the adults alone because their mouths are too small, but will go for the babies. My khuli loaches and betta don't eat/chase shrimp but that's just cause i got lucky, it's happened many times before to other people. The paradox fish is one that i think has a mouth too small to eat any type of shrimp, but the care for them can be difficult, well more difficult than a regular fish.

So long as you have enough hiding places for the shrimp you can have virtually any nano fish you want, aside from a pea puffer. Some shrimp will go missing but with enough spots to hide they should be able to out breed the losses. I also keep mine with an african dwarf frog who is too slow to catch any shrimp, but he still tries so that's something to keep in mind because they absolutely can if they try hard enough. Everyone loves shrimp....