Some years ago, our neighbors up the branch dug a small "oriental" pond. The, of course, put some small Koi in. The spring rains here can swell the branch well beyond the width of their little water feature. Hence, the two Koi they put in have washed into my three acre pond and are now in the 19 to 22 inch size. They must be the same sex, because there is no sign of little ones. Will these hurt my pond in any way or can the peaceably cohabit with my Bass,Brim and Pearch?