the peak height of biomass density of golden apple snail is higher with more fluctuations and the time for the peak to occur is faster. In particular, if comparing when increases from 1 to 2.5, the first peak of golden apple snails occurs about 9 days earlier. On the other hand, the result shows that the peak height of Asian openbill gives no change, although the time for the peak to occur is faster than those of smaller .