Tank details are helpful -
Size
Hardscape
Plants
Fish
Shrimp “tubes” etc will need to be shrimp only accessible - not so easy as shrimp often seem to want “antennae room”
Pretty much fish will try if anything is edible ... I’ve seen relatively small fish kill adult shrimp - it may take a few “hits” vs gulping down shrimp whole, but some effort to immobilize shrimp and then dine at leisure (well, except for the descending horde of other interested parties)
Other times fish seem to pretty much ignore shrimp, even when fish are same species as above observed behaviour - but different group - once a Shrimp Hunter, always a Shrimp Hunter
Stressed shrimp will display more “prey” behaviour than established shrimp, so having a minimum of 10-12 adult shrimp, placing them in the tank first etc tends to improve shrimp success
Once shrimp colony reaches a certain population, it tends to carry on despite predation (imagine sturdy cherry shrimp types rather than OEBT etc)
If your intention is to see the shrimp out & about, this won’t happen unless fish display minimal interest
Useless anecdote:
Display tank with only shrimp (various species as part of display) for a couple months, shrimp were always visible, could also readily see babies about
Guppy trio added
Within a couple days, shrimp were much less visible and babies were no longer seen (though they may’ve been in rock crevices etc)
Shrimp still came out en masse for special (shrimp) food, but it really was no longer effective as a shrimp display tank
When tank was sold and shrimp caught, there were several (smaller species) favorites that were MIA
At no time, were guppies observed determinedly harassing/chasing shrimp - but they did approach and display interest (& I suspect did account for the MIA babies etc)