This paper discusses about simulation methods for behavior of swimming Scallop larva. Diverse aquatic organisms exist as a larva under the water after birth. The larva moves and spreads according to flow condition, water temperature, salinity etc. Prediction of behavior of the larva is important and useful to manage sustainable fishery resources and fishing ground. Authors tried to simulate the behavior by means of two methods. One is concentration tracer method and the other is particle method. Applicability of both methods was examined based on comparison with field measurement data set in Lake Saroma. It was shown that particle method has high potential as a prediction method for behavior of the larva in Lake Saroma.