Abstract: Traditional freshwater aquaculture is facing more and more serious environmental problems, and thus, ecological remediation technologies for freshwater pond environment are more attracted. The insitu remediation represented by fish-vegetable mutualism mode (FVMM) and the ectopic remediation represented by recirculating aquaculture system (RAS) are the emphases of present researches. From the viewpoint of water eutrophication, and with pond nitrogen cycle as the point of penetration, this paper analyzed the advantages and disadvantages of FVMM and RAS, and discussed their referred area configuration. The FVMM could reduce the discharge coefficient of fish pond, but the ecological balance would be hard to realize if this mode was applied to all our fish ponds. The RAS could not avoid the extra economic cost and land resources, but its zerodischarge made this system have definite ecological value when applied in eutrophication area.

Key words: niche, ecology.