White Cloud Minnows..?

If you have room for 6, get 6. If you have room for 7, get 7. Minnows are schooling fish, and schooling fish will feel more comfortable in larger groups. 5 is the absolute bare minimum. In groups smaller than this, your fish will hide all the time, become stressed, and perish easily. The more fish you have in a school, the more active, lively, and interesting they will be.