The results of gastric evacuation rate (GER) experiments can be used to estimate the stomach fullness in ornamental fish at a postprandial time, which will avoid their over- and under-feeding. The influences of fish size L (cm), meal size, and temperature T (degrees C) on GER of ornamental Jewelfish (Hemichromis bimaculatus) fed formulated feed were examined. Fish used in these experiments were ranged in sizes (total length L) from 6.3 cm to 9.5 cm that were fed a range of different meal sizes ranging from 0.12 g to 0.29 g. The evacuation of feed from the stomach of H. bimaculatus was best described by the so-called surface-area dependent model independently of meal size. The relationship between GER and temperatures was then described using an exponential model while the effects of fish size on the GER was determined by the simple power function of L. The GE model of H. bimaculatus fed formulated feed could thus be described by (ds)t/dt = -0.000333 L-0.76 e(0.15)T s(t)(2/3) (g h(-1)), where S, is current stomach contents mass (g) and t is time (h). This model should estimate the stomach fullness of H bimaculatus at a postprandial time, which could have an application in the planning of feeding routines for the studied fish.