【Objective】 This paper intends to determine the bioactiuity and enhancement on non-specific immunity and survival of secondary metabolite of strain SX-4 on carp(Cyprinus carpio).【Method】 A thermophilic strain SX-4 able to produce immunostimulatory metabolite was isolated from sludge sample of hot spring and identified by comparison with 16S rRNA sequences(99% of homology) as Anoxybacillus flavithermus.【Result】 Through bioactivity-guided fractionation of methanol extract from its cell-free culture,one bacter...