Agricultural fields and irrigation water are the most fundamental resources for crop production and are needed to strengthen to keep good conditions for sustainable development of agriculture. To enrich the biological diversity both green corridor such as crop fields, orchards, trees inside the residental area and forest in the sacred area for the migrations of mammals and birds, and the aquatic corridor such as irrigation and drainage channnels, farm ponds are necessary to be sattled. Study was conducted in the typical flat paddy field area with well-prepared irrigation facilities. Irrigation water was continuously over flooded. Differences of fish species were observed in each water channnels. Some ideas to evaluate the water channnels on the biological conformity potentials for aquatic animal inhabitant are proposed, after observing the water networl system. To evaluate the effectoveness on animals migration, the characteristics of channnel unit and connectivity are classfied. The biological conformity potentials of each channnel units were evaluated by indexes on connectivity, hydrology and environment were applied. The results showed that water management also have some influences on the potentials. From the observations on the biologocal conformity potentials in both irrigation and non irrigation seasons, it was conducluded that constructing the fish ways, step type weir, detour channnel and so on, are not so effectove on drainage but much more effectove on irrigation-drainage channnels.