We stored oysters ready for shipment in fish tanks for 5 days in order to investigate the effects of baits and water temperatureson their taste compositions. Three plankton species, Nannochloropsis sp., Chaetoceros calcitrans, and Chaetoceros gracilis wereemployed as baits, and the study was conducted at 10°C and 20°C. There were 7 oyster groups including a control group. Forthe group of the oysters fed on Nannochrolopsis sp. and monitored at 10°C, the level of alanine, which is related to sweetness,was significantly higher than those found in the control groups. The level of phenylalanine, which is related to bitterness, wassignificantly lower in all bait groups than in the control group. Among all groups, no difference was exhibited in the levels of AMPand glycogen, nor in the sensory evaluation. The oysters stored at 20°C showed decreased levels of a number of free amino acids.This was especially so for those fed on the Nannochrolopsis sp. in which the level of AMP and the scores obtained in the sensoryevaluation were also low. It can therefore be concluded that an improved taste may be imparted to oysters by storing them withplankton baits. A storage temperature of 10°C yielded better results than those obtained at 20°C.