If it is truly a dwarf crayfish (Cambarellus patzcuarensis AKA CPOs), which it appears to be, then it can live with fish. Dwarf crayfish get no bigger than 1.5-2 inches and their pinchers are tiny. They can't catch and eat a fish unless it is already sick and dying or something.
In fact, the dwarf crayfish are the ones who could be in danger in a tank with fish. When they molt they are very vulnerable and would need safe hiding spots. And larger fish could eat them no problem.
It would probably be ok with guppies or platies. But the crayfish could possibly harm the ghost shrimp.
More than 10 years
Is it safe to put one in my 15 gallon with 4 guppies, 1 platy and 1 ghost shrimp?[/QUOTE]
I have one in a 3.5 gallon tank with a betta and an Amano shrimp, they all ignore each other, btey are too tiny to bother too much, I would hesitate with dwarf shrimp or tiny fish however.