Although black stone carp(Pseudopungtungia nigra) has been found in several streams so far, its distribution is confirmed to the brooks such as Man Kyeong, Keum and Ung Cheon. These brooks have special features in common that the bottom is ruggy and shallow, thus allowing the rapids appear. This condition would be advantageous in making more light available for growth of algae. The higher density of the black stone carp population in Ung Cheon is largely depend upon the richness of fresh water green algae attached on the substratum or pebbles in the rapids. Because the black stone carp is primary consumer in brook ecosystem it wanders mainly the space between subbottom and bottom in brooks, where Zacco platypus, Microphysogobio longidorsalis, M. koreensis and M. yaluensis are also found.