A semi-field confined assessment of a native larvivorous fish, Aploclleilus latipes (Temminck & Schlegel) was conducted at the release rate of 2.0 mature fish per 1-M$^2$water surface over simulated rice paddies (3.0$ imes$2.5$ imes$0.5m) in the Aquatic Outdoor Laboratory of NIH in the period of June through October in 1985. Fish introduction in mid-July resulted in a significant malaria vector (Anopheles sinensis Wiedemann) mosquito reduction by 60.1% in comparison with that of control plots in one week, and subsequently, the mosquito control rate increased to 64.9 % in a period of one month after the fish release. During later August through September, vector population increased up to an average of 137.8 larvae per sample which had been maintained throughout the period, and the mosquito control recorded rather lower minimum in a range of 53.1~65.4% presumably due to heavy growth of aquatic weeds and algae. In October, the control rate of mosquito larvae restored to 64.9% which sustained until October 15-th with an increased control rate of 69.7%. An overall average in the reduction of the target vector (An. sinensis) by fish release was 61.5%, the results being considered a significant but substantial malaria vector control. It is suggested that in condition of heavy weed or algae growing rice paddy habitat, biological control of fish predator, Aplocheilus against malaria vector mosquito larvae should require complementary technique using herbivorous fish such as Tilapia sp. in order to make an effect to the synergistic role in getting rid of aquatic weeds for the predator fish to prey on larvae with ease.