Male Betta or Male Betta splendens have more interesting performance than female Betta splendens. Due to the case, male Betta splendens are more expensive than the female ones. One of the techniques to create male Betta is by adding hormone 17 –α methyl testosterone (mt). But nowadays the use of that hormone is forbidden. One of the alternative substitutions is by using Aromatase Inhibitor (AI). The aim of this study is to find out the influence of hormone Aromatase Inhibitor (AI) within different dosage on larva stadia (six days after hatching) to the sex ratio and to find out the optimal dosage of AI that creates male Betta splendens. The method used in this study is Completely Random Design (RAL) by five treatments and three times repetition within AI dosage 0, 5, 10, 15, 20 mg/l. The data then be analyzed using ANOVA. If the result comes well, Polinominal orthogonal does next analysis. The result of this study is that within dosage 20 mg/l creates the highest percentage male as much as 50,28%, in the D treatment 45,46%, in the C treatment 39,76%, in the B treatment 31,85%, and the lowest percentage is at 0 mg/L as much as 24,48%. The water quality in this study is very appropriate to the growth of Betta splendens that is within the temperature at 27 – 29oC, pH 7, 5-8, DO 5, 1 ppm.
Key words: hormone aromatase inhibitor, betta splendens, sex ratio.

• PENGARUH PERENDAMAN HORMON AROMATASE INHIBITOR (AI) DENGAN DOSIS YANG BERBEDA PADA STADIA LARVA TERHADAP NISBAH KELAMIN IKAN CUPANG (Betta splendens)