What is the best fish to put in with 3 red clawed crabs?

I'm scared the crabs will nip or kill the fish. I also put in some water conditioner because i use regular water and this conditioner has salt in it. I have a 10 gallon tank about half way full and access to land for the crabs through a tall plant, i can put more water in for the fish and i have a heater, thermometer, and good filter. (: