Effect of high temperature on production of males in siamese fighting fish (Betta splendens) population

Abstract

In Betta splendens, male was more valuable than female in market. So, study was done to determine the effect of high temperature on sex ratio and the number of male on Betta splendens. Larvae were produced through natural breeding and exposed to two different temperatures which were 28° C and 30° C. The larvae were reared for 60 days to determine the sex ratio and number of male. Observation was done based on the morphology, sexual organ and behaviour. Result of the experiment showed that, rearing juvenile at 30°C produced higher number of males (68.59±1.20 %) compared to 28° in which the number of male to female was the same or the number of female were more (57.15%). Statistical analysis using Chi-square showed that, sex ratio of fries reared at 30°C was 2: I ratio (male: female) compared to 28°C which was I: I and I: 1.5 (male: female). This study showed that, higher number of males can be produced at high temperature. Further study on Betta splendens exposure to high temperature should be done to determine the mechanism of sex changes in this fish. Thus, this method could be applied to the production of Betta splendens males in aquaculture.