By results of fish experiments with which fish reefs areas and control areas were compared, the reef affinity index was defined and calculated. And, the results of the fish experiments classified by distance were applied to an approximate expression and the distance distribution from fish reefs of the fish species was quantified. It was suggested that fish reef affinity was formed by acquisition competition to feed during of the fish species and food chain. From results of the reef affinity index and the distributions of fishes, it was shown to be able to presume the attracting amount from the distribution of fish. And relational expression H=N_0-N_0・e^<-AC_V×bV>+N_0・AC_S・e^<-AC_V×bV> of the stock abundance N_0, the attracting amount H and the fish reefs volume bV was proposed.
