my tank set up is a 10 gallon tank with 1 mountain minnow, 2 bait shop minnows, and 2 goldfish. all these guys grew up together so they dont try to eat each other.
one of the goldfish is big enough to eat the cloud. but it is used to goldfish. i got the cloud for free when i bought my goldfish because walmart didnt kow what it was. there was just a little tiny mystery fish in with a tank full of goldfish 10 times bigger than it.

my advise would be to get the smallest goldfish you can find and let them get used to the cloud minnows. they should get along then.