The zebra danio is a type of freshwater schooling fish. They make good pets for those who are inexperienced in aquarium-keeping because they are very hardy and thrive in a wide range of water temperatures and conditions. They are called "zebra" danios because of the long black stripes on their silver bodies. These fish do best in groups of six or more, but since they are so small - they don't grow to be more than two inches long usually - and also cheap ( no more than $1.50 apiece usually) this should not be a problem. When in a group they school, meaning they all swim together - there may be some aggression between particular fish but they are fast swimmers so it rarely leads to injury. The zebra danio exists in a more natural state in the quick-flowing rivers and streams of India - therefore they enjoy a strong current from an aquarium filter to swim in. Ideally they should be kept at a water temperature from 60-80 degrees Fahrenheit, in a long tank (rather than a tall hexagon type tank) of 5 gallons or more, depending on how many you have. They do well on a generic flake food diet, and get along well with nearly all other fish.
http://www.aquariumfish.net presents many helpful tips on taking care of fish, in addition to zebra danios