Danio rerio (Ostariophysan cyprinid), a tropical fish breed popular with hobbyists, are available at pet stores throughout the world. The equipment, food, and supplies needed to raise them are also readily available. Zebrafish can be easily maintained in aquaria that has been heated to 28.5oC (83oF) [Above 31oC (88oF) or below 25oC (78oF), zebrafish probably will not breed and development will be abnormal.], and their durability and active lifestyle make them ideal for the classroom.