I also had this concern when I created my snail trap as I have some small fish in my tank (harlequin rasboras, white cloud minnows, danios, not to mention assassin snails and my favourite nerite snail). After looking online, I came across this solution, and I didn't get any of my fish in there.
It is a cheap ziplock plastic container...I had to trim the top edges so I could fit the hole punch over the rim, then I hole punched it.
I then placed some gravel ( big mistake btw, better to use 1 large pebble unless you want to be picking through the stuff to find the snails - yuck!) and a piece of cucumber and a algae wafer into the container and placed it into the tank over night ( I even placed a towel over the tank to make it super dark longer). This is what I woke up to this morning!
After picking throw the gravel ( again, yuck) I found these snails which I crushed and froze for a special treat for my fish at a later date ( to crush them, fold a paper towel over the bag, place it on a hard surface and use something else hard to crush them, don't use your fingers unless you want a chunk of snail shell cutting through your finger ( really!).
I find my fish ( all of them) go wild for these one a week.
Sent from my iPad using Aquarium Advice
