PROBLEM TO BE SOLVED: To improve water quality by using a habitat environment which enables aerobic Miroku spawn to live in a napping state and its activation in service water by releasing napping. SOLUTION: In the habitat environment, its core is made of charcoal, and water, oxygen, food, and a microorganism are controlled so that they can be timely and properly supplied. The habitat environment has a string facilitating putting in and out of the environment, and has a recovery means against contamination, which enables efficient purification and improvement of various kinds of service water. COPYRIGHT: (C)2006,JPO&NCIPI